GLpH instruction manual May 2008

Transcription

GLpH instruction manual May 2008
This manual gives general instructions for using the Sirius GLpH laboratory pH measurement instruments
fitted with Revision 3 software.
Publishing history:
March 1996
GLpH instruction manual revision 1.0. Instructions for GLpH with Version 1
Hardware and Revision 1 software.
August 1997
Hardware and Revision 1 software. Update of manual revision 1.0
November 1997
Hardware and Revision 2 software.
March 1998
Hardware and Revision 2 software. Update of manual revision 3.0.
May 2008
Hardware and Revision 3 software. Update of manual revision 4.0.
Copyright © 2008 Sirius Analytical Ltd.
This document is prepared for the users of the Sirius GLpH. All rights are reserved. No part of this document may be reprinted, or
reproduced or utilized in any form by any electronic, mechanical or other means, now known or hereafter invented, including
photocopying or recording, or in any information storage or retrieval system, without permission in writing from Sirius Analytical Ltd.
GLpH, and Four-Plus are trademarks of Sirius Analytical Ltd. Triton X-100® is a registered
trademark of Rohm & Haas Corporation. Windows® is a registered trademark of Microsoft
Corporation.
Sirius Analytical Ltd
Riverside
Forest Row Business Park
Forest Row
East Sussex RH18 5DW
UK
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CONTENTS
1. Foreword ............................................................................................................................5
1.1. GLpH safety ................................................................................................................5
1.1 Versions of hardware and software .............................................................................5
1.2 GLpH exists in two different hardware versions ..........................................................5
1.3 How to check which version of hardware you have.....................................................6
1.4 GLpH also exists in three different software Revisions ...............................................6
1.5. How to check which revision of software is installed in your GLpH............................6
1.6 Secret codes ................................................................................................................7
2. A brief theory of pH ............................................................................................................9
2.1 The meaning of pH.......................................................................................................9
2.2 pH electrodes ...............................................................................................................9
2.3. Buffer solutions..........................................................................................................10
2.4. pH Scales ..................................................................................................................10
2.5. The concentration pH scale ......................................................................................10
2.6. Temperature effects ..................................................................................................11
2.6.1 Temperature dependence of slope .....................................................................11
2.6.2 Temperature dependence of the internal components of the pH electrode .......11
2.6.3 Temperature-dependence of buffer solution pH values......................................12
2.6.4 Temperature dependence of sample pH.............................................................12
2.7 Calibrating and measuring pH on the operational scale............................................13
2.8 Measurement of low and high pH values...................................................................13
3. GLP and pH .....................................................................................................................14
3.1 Introduction.................................................................................................................14
3.2. Testing of instruments and components ...................................................................15
3.3 Testing and validation of software .............................................................................16
3.4 Installation Qualification and Operational Qualification (IQ and OQ) ........................16
4. Setting up GLpH ..............................................................................................................17
4.1 Overview ....................................................................................................................17
4.2 Electrical connections ................................................................................................18
4.3 Packing checklist........................................................................................................19
4.4 Setting up GLpH hardware for the first time...............................................................19
4.4.1 Setting up GLpH single-sample version ..............................................................20
4.4.2 Setting up the GLpH and autosampler ................................................................21
4.5 Installing the cable sheath..........................................................................................23
4.5.1 New probes..........................................................................................................23
4.5.2 Replacing probes.................................................................................................24
4.6 Setting up GLpH for the first time...............................................................................24
4.7 Operational Qualification............................................................................................25
5. Calibrating GLpH .............................................................................................................27
5.1 Why calibrate?............................................................................................................27
5.2 Overview of GLpH calibration ....................................................................................27
5.3 Changing the calibration buffers ................................................................................27
5.4 Calibration protocols ..................................................................................................29
5.5 Choice of buffer solutions...........................................................................................30
5.6 pH 7 buffers................................................................................................................30
5.6.1 Using other buffers ..............................................................................................31
5.7 During and after calibration... .....................................................................................31
6. Measuring pH...................................................................................................................33
6.1. Measuring pH with single-sample version ................................................................33
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6.2. Measuring pH with autosampler version of GLpH ....................................................33
6.3. Measuring pH in large beakers .................................................................................34
6.4 Measuring pH using small vials..................................................................................35
6.5 Special wash solutions...............................................................................................36
6.6 Special electrode clean ..............................................................................................36
7. Methods ...........................................................................................................................37
7.1 Overview of automated pH measurement .................................................................37
7.2 Factory-set default methods.......................................................................................37
7.3 Creating methods .......................................................................................................39
7.4 Editing methods..........................................................................................................39
7.5 Step-by-step guide to methods ..................................................................................39
8. Setup................................................................................................................................44
8.1 System Setup .............................................................................................................44
8.1.1 Setup/System setup/System Lock code..............................................................44
8.1.2 Setup/System setup/Serial port output to............................................................44
8.1.3 Setup/System setup/Autosampler tray type default ............................................44
8.1.4 Setup/System setup/Lock system on calibration failure......................................44
8.1.5 Setup/System setup/Lock system on calibration suspect ...................................45
8.1.6 Setup/System setup/Use Sample IDs .................................................................45
8.1.7 Setup/System setup/Prompt last sample IDs......................................................45
8.1.8 Setup/System setup/Increment sample ID ..........................................................45
8.1.9 Setup/System setup/Temp probe in sample measurements ..............................45
8.1.10 Setup/System setup/Print sample results .........................................................45
8.1.11 Setup/System setup/Allow emergency sample interrupt...................................45
8.1.12 Setup/System setup/Do calibration after...........................................................45
8.1.13 Setup/System setup/Use audit trail log .............................................................46
8.1.14 Setup/System setup/Use user names ...............................................................46
8.1.15 Setup/System setup/User ID PIN numbers required ........................................46
8.1.16 System setup/System setup/Add user during test ............................................46
8.1.17 Setup/System setup/Show electrode slope as..................................................46
8.1.18 Setup/System setup/Print calibration log ..........................................................47
8.2 Setup/Setup time and date.........................................................................................47
8.3 Setup/Set calibration protocol ....................................................................................47
8.4 Setup/Install electrode, electrode parameters ...........................................................47
8.4.1 Installing a new pH electrode ..............................................................................47
8.4.2 Setting up out-of-range parameters for electrode, buffers and calibration .........47
8.4.3 Serial numbers for electrodes and temperature probes......................................48
8.5 Setup/Enter user names ............................................................................................48
8.6 Setup/Setup actions and reminders...........................................................................48
8.6.1 Automatic calibration, Reminders to carry out maintenance functions ...............48
8.6.2 Automatic electrode calibration ...........................................................................48
8.6.3 Install fresh wash solutions .................................................................................49
8.6.4 Install fresh pH7 buffer solutions .........................................................................49
8.6.5 Refill electrode with filling solution.......................................................................49
8.6.6 Order new reagents/consumables ......................................................................49
8.7 Setup/Enter special wash names...............................................................................49
8.8 Setup/System test options .........................................................................................49
9. Audit .................................................................................................................................50
9.1 Overview ....................................................................................................................50
9.2 Audit functions............................................................................................................50
9.2.1 Calibration slope history graph............................................................................50
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9.2.2 Calibration E0 graph ............................................................................................50
9.2.3 Calibration history data........................................................................................51
9.2.4 pH buffer drift history ...........................................................................................51
9.2.5 Sample results data.............................................................................................51
9.2.6 Result record indicates deviation from GLP........................................................52
10. Display and text entry ....................................................................................................53
10.1 Display......................................................................................................................53
10.2 Keypad, computer keyboard ....................................................................................53
10.3 How to enter text into GLpH.....................................................................................53
11. Output from GLpH..........................................................................................................55
11.1 Output to printers......................................................................................................55
11.1.1 Types of printout................................................................................................55
11.1.2 Printers fully supported by GLpH ......................................................................55
11.1.3 Setting up GLpH for communication with printer...............................................56
11.1.4 Other printers.....................................................................................................56
11.1.5 Setting up a printer for communication with GLpH............................................56
11.1.6 Cables to connect GLpH to printers ..................................................................56
11.1.7 Connecting the printer .......................................................................................57
11.2 Using GLpH with computers ....................................................................................57
11.2.1 Types of data output from GLpH .......................................................................57
11.2.2 Setting up a PC for communication with GLpH.................................................57
11.2.3 Cables to connect GLpH to PC .........................................................................57
11.2.4 Setting up GLpH for communication with a PC.................................................58
11.2.5 Using HyperTerminal to capture text data downloaded from GLpH .................58
11.2.6 Downloading data from GLpH to a PC running HyperTerminal ........................60
11.2.7 Example of downloaded calibration data ..........................................................60
11.2.8 Example of downloaded sample results data....................................................62
11.2.9 Interpreting the code..........................................................................................62
11.2.10 Example of downloaded hourly pH7 mV (E0) data..........................................63
12. Troubleshooting .............................................................................................................64
12.1 Electrode troubleshooting ........................................................................................64
12.2 Maintenance menu...................................................................................................64
12.3 Lubrication................................................................................................................65
12.4 Electromechanical problems ....................................................................................66
12.5 Selftest options.........................................................................................................67
12.5.1 Test and set clock chip ......................................................................................67
12.5.2 Test hardware....................................................................................................67
12.5.3. Keyboard and keypad.......................................................................................68
13. Parts and accessories ...................................................................................................69
13.1 Ordering parts ..........................................................................................................69
14. Using Auto-Run..............................................................................................................71
14.1 Overview ..................................................................................................................71
14.2 Instructions ...............................................................................................................71
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1. Foreword
1.1. GLpH safety

Please read the instructions before carrying out any work using GLpH.
Always ensure the instrument is switched off at the mains before removing the top cover (blue metal
lid), or any other item of the instrument.
Never run the instrument without the top cover in place.
Do not put your hand or any tools inside GLpH while it is switched on.
Do not place anything on the top cover - it is liable to be knocked off by the tower motion from left to
right.
Do not immerse the instrument in liquid - if you wish to clean it wipe it only with a damp cloth - avoid
using abrasive cleaners, detergents or organic solvents to wipe it. Some items which you may wish
to wash more thoroughly are detachable, e.g. wash beakers, vials, sample beaker station.
Avoid spillages near the instrument - if you do spill something on or near the instrument it may get
into the electrics. In this instance it should be switched off immediately.
Do not attempt to work on the electrics within the instrument - call a trained service engineer if you
have a problem.
Ensure you follow the instructions for correct location of samples etc. - an incorrectly positioned
sample could cause the electrode to get broken! Always ensure the electrode has a clear path
before using the instrument.
1.1 Versions of hardware and software
There are several different versions of GLpH instruments.
1. GLpH single sample instrument with Version 1 Hardware and Revision 1 software
4. GLpH with autosampler, with Version 2 Hardware and Revision 2 software
6. GLpH with autosampler, with Version 2 Hardware and Revision 3 software
This instruction manual describes only the operation of GLpH with Revision 3 software.
1.2 GLpH exists in two different hardware versions
1. GLpH single-sample instrument, Version 1 Hardware (shown in Figure 10). All GLpH instruments
supplied in single-sample format before mid-1998 are fitted with Version 1 Hardware. Instruments
fitted with Version 1 Hardware cannot be used with the autosampler unless they are converted to
Version 2 by a service engineer.
2. GLpH single-sample instrument, Version 2 Hardware. All GLpH instruments supplied with
autosamplers are fitted with Version 2 Hardware (complete system shown in Figure 9). It is planned
that all GLpH single-sample instruments will be fitted with Version 2 Hardware from about mid-1998.
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1.3 How to check which version of hardware you have
1. Vial locating plates are different (see Figure 1)
2. Electrode holder in Version 1 is longer than in Version 2. See Figures 9 and 10.
3. There are some internal differences.
Figure 1. GLpH vial plates
1.4 GLpH also exists in three different software Revisions
Revision 1 software was installed in all GLpH single-sample instruments fitted with Version 1 Hardware, and
supplied before about mid-1998.
Revision 2 software is installed in all GLpH instruments fitted with Version 2 Hardware, including all GLpH
instruments supplied with autosamplers. Revision 2 software can also be installed in GLpH single-sample
instruments fitted with Version 1 Hardware (part number 0905011 for software upgrade).
Revision 3 software was created in 2008 and runs on a new PCB, v. 5.a.
1.5. How to check which revision of software is installed in your GLpH
Switch on GLpH. The software revision level is displayed while the instrument initialises itself (see Figure 2).
Figure 2. GLpH display just after switching on
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1.6 Secret codes
Users must enter secret codes to gain access to certain features of GLpH software.
Remove this page if you do not want unauthorised
persons tampering with the instrument!
Action
When can you enter
code?
Code
To go from Main Menu to
System Variable Initialisation.
This allows you to state whether
the system has an autosampler,
and to initialise all userprogrammable variables.
When the Main Menu
is displayed.
1.4142
To go from the Normal User
Menu to the Supervisor menu
without entering a lock code.
When the Normal User
Menu is displayed
0.9999
To by-pass an error message
without switching off the
instrument (See Section 12.4).
If the instrument is
beeping once per
second, and an error
message is displayed
Type 0 1 2 3 4
at the rate of
one character
per beep.
To set up the distributor’s name,
address and other details
In About/Your
Distributor Contact
Information, when
Distributor’s name and
address is displayed
Type s e t on
a computer
keyboard
attached to
GLpH
Alternatively,
hold down 8
and 9 when
switching on
the instrument
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8
2. A brief theory of pH
2.1 The meaning of pH
The term pH is a number which expresses the “concentration” of dissolved hydrogen ions in solution. It is
used to express the relative strengths of acids and bases. The concentration of hydrogen ions in strong
acids is very high, while in strong bases it is very low. The "p" in pH means "-log10", so pH is a logarithmic
function. Thus, a 0.3%w/v hydrochloric acid solution with pH = 1 is 1,000,000 times greater in hydrogen ion
concentration than de-gassed, deionized water with pH = 7. The pH of a solution is measured using a glass
pH electrode connected to a suitable instrument.
2.2 pH electrodes
A glass pH "electrode" actually consists of two half-cell electrodes, one with a membrane made from a
special type of pH-sensitive glass, and the other a reference half-cell (Figure 3). When these electrodes are
placed in a solution a voltage is generated between them, and the voltage (expressed in millivolts, mV) is
related to the pH of the solution. In Figure 3, a represents the internal filling solution; b is the internal
reference electrode (silver/silver chloride in KCl solution saturated with AgCl); c is the external filling solution;
d is the pH-sensitive glass membrane; e is the internal liquid junction and f is the external liquid junction.
Figure 3. Construction of pH electrode.
a represents the internal filling solution;
b is the internal reference electrode (Ag/AgCl in KCl solution saturated with AgCl);
c is the external filling solution;
d is the pH-sensitive glass membrane;
e is the internal liquid junction;
f is the external liquid junction.
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2.3. Buffer solutions
Buffers are solutions of fixed composition which have pH values that have been defined by international
standards organizations like NIST, DIN and BS. Buffers are used for calibrating pH electrodes. See Section
5.5.
2.4. pH Scales
There are several different pH scales.
The fundamental scale is the activity pH scale, which is defined in terms of the activity of hydrogen ions in
solution. Although it was used by Bates and other scientists who first determined the pH values of standard
buffer solutions, the activity scale is impractical for everyday work.
The most commonly used scale is the operational pH scale, which is the scale used by GLpH. In this scale,
one or more standard buffer solutions are recognized as fixed pH points on the scale. A pH electrode is
placed in each of the buffer solutions and the mV reading E is taken when it has reached a stable value. A
straight line is fitted to the mV vs. pH points. This straight line is described by the equation below, which is
based on the Nernst equation.
pH(X) = pH(S) −
(E − E 0 )
RT
2.303
F
Where:
E is the mV reading of the electrode in a solution with a pH value of pH(X).
Eo is the mV reading of the electrode in a buffer solution with a pH value of pH(S).
2.303 RT/F is the Nernst slope, which is 59.16mV/pH at T= 298.15K (25°C) for an electrode with
perfect behaviour.
There is also a concentration pH scale, which is described below.
2.5. The concentration pH scale
Figure 4. Comparing pH scales: Operational vs. Concentration
Figure 4 is based on the concentration pH scale, which may provide a better way to measure extreme pH
values than the operational scale. This scale is based on the activity scale, but standardization and
measurement are done at constant ionic strength. Ionic strength is kept constant by adding a strong solution
10
of background electrolyte. When ionic strength is constant, activity is proportional to concentration. The
operational scale and the concentration scale are related by the following equation:
pH = α + Sp[H] + jH [H + ] + j OH [OH − ]
where:
pH
p[H]
α
S
jH
jOH
= pH measured on operational scale (“what the pH meter reads”)
= pH on concentration scale
= -logγ, where γ = activity coefficient of hydrogen ion
= ratio between the actual slope and the Nernst slope
= correction factor for liquid junction potential at low pH
= correction factor for liquid junction potential at high pH
This equation is the basis of the Sirius Four-PlusTM technique of pH electrode standardization. Mean values
of α, S, jH and jOH for a well-performing pH electrode have been experimentally-determined, and applied in
Figure 4 to show the relationship between the two scales. Figure 4 shows a comparison between the
concentration pH scale and the activity of hydrogen ions at various concentrations of HCl. The curves are
almost parallel above pH2 (and below pH12!) though they will deviate slightly if S≠1.0000. The offset
between the two curves is a consequence of the value of α. The deviation at low pH is a consequence of
liquid junction potential.
Sirius have developed an in-house procedure based on Four-Plus for testing pH electrodes.
2.6. Temperature effects
2.6.1 Temperature dependence of slope
Figure 5. Ideal electrode, isopotential 0mV at pH7
Electrode slope increases with temperature, as shown in Figure 5. The isopotential point of the pH electrode
is the point where the mV reading does not depend on temperature. pH electrodes are generally
manufactured such that the isopotential point is E = 0mV and pH7, corresponding to E0 and pH(S) in the
equation in Section 2.4.Because of difficulties in manufacture and the fact that electrode performance
changes with time, the isopotential point may vary slightly in a poorly understood manner.
2.6.2 Temperature dependence of the internal components of the pH
electrode
The potential of silver/silver chloride internal reference elements changes with temperature. This is because
the solubility of the silver chloride precipitate in the filling solution changes with temperature. Readings of pH
electrodes which use silver/silver chloride tend to be unstable when the electrode is placed in samples of
11
differing temperatures. This type of temperature effect is largely eliminated in pH electrodes in which the
reference element is a platinum wire in contact with an iodine solution, with no solid salt phase.
2.6.3 Temperature-dependence of buffer solution pH values
The pH values of buffer solutions change with temperature. GLpH measures the temperature of solutions
while calibrating, and assigns a pH value for the buffer which is correct at that temperature. Tables of pH
values at selected temperatures are published in NIST, DIN and BS standards. Values from these tables are
built in to GLpH. To enable GLpH to assign a pH value at any temperature by interpolation, it fits the
pH/temperature data taken from the tables using a polynomial procedure. The curves of fitted data which are
used are shown in Figure 6.
Figure 6. Temperature-dependence of buffer solution pH values
Key to Figure 6
Variation of pH with temperature (T) in 0C for the six standard buffer solutions specified for use with GLpH.
The curves are based on published data of pH at various temperatures [1,2,3]. When GLpH is calibrating a
pH electrode, it measures the temperature of the buffer solution and calculates the pH of the buffer using this
equation, and coefficients A0 to A3 as shown in Table 1.
pH = A0 + A1(T) +A2(T2)+A3(T3)
A0
A1
A2
A3
pH1.68 1.666408 0.000211 1.1E-05
2.73100E-08
pH4.00
3.99739 -0.00014 2.7E-05
pH6.86
6.97169 -0.00512 4.5E-05
pH7.00
7.11702 -0.00742 0.00013 -7.25700E-07
pH9.18
9.46268 -0.01419 0.00013 -5.17100E-07
pH10.0 10.31709 -0.01501 0.00012 -3.04600E-07
Table 1. Coefficients for calculating variation in buffer pH with temperature
[1] J. Res. N.B.S 1962, 66A, 179; [2[ BS6068, 1995, 2, 2.50; [3] DIN19266
2.6.4 Temperature dependence of sample pH
The pH values of samples change with temperature in a way that is very difficult to predict. For this reason,
pH results should be reported at the temperature at which they were measured. It is rarely possible to
12
convert a pH value of a sample measured at a particular temperature to an equivalent pH value for the same
sample at a different temperature.
2.7 Calibrating and measuring pH on the operational scale
In GLpH, pH electrodes are calibrated on the operational scale by placing them in two or three buffer
solutions and recording the mV in each solution and the temperature, defining the pH of each buffer at that
temperature, then joining the mV/pH readings by straight lines. Two- and three-buffer calibrations are shown
in Figures 7 and 8. After calibration, pH is measured by placing the electrode in a sample, recording the
voltage and the temperature, correcting the electrode slope for temperature, then calculating the pH by
comparing the voltage against the calibration graph. GLpH carries out this process automatically.
Figure 7. Two-buffer calibration of GLpH at 25°C. Calibration protocol no. 1 in use (pH4 and 7). Slope
value of 58.3 mV/pH applied in all measurements of pH
Figure 8. Three-buffer calibration of GLpH at 25°C. Calibration protocol no. 3 in use (pH4, 7 and 10).
Slope value of 58.3 mV/pH applied in measurements of pH below 7. Slope 58.7 mV/pH applied in
measurement of pH above 7.
2.8 Measurement of low and high pH values
The pH/mV lines in Figures 7 and 8 are extrapolated to pH0 and pH14. However, it is not possible to rely on
these extrapolations to make accurate measurements of pH below about pH1.5 and above pH12, where pH
readings are strongly affected by liquid junction potentials and ionic strength effects, and the operational pH
scale becomes unreliable. The problems are illustrated in Figure 4, which shows a comparison between low
pH values as they might be read on GLpH and equivalent values calculated as -log10[H+].
13
3. GLP and pH
3.1 Introduction
"The principles of good laboratory practice (GLP) are based on a simple
philosophy: the basic idea is that laboratories should design, perform and report
... studies on chemicals and preparations carefully and should document all
activities in such a way that the studies can be reconstructed at any time
afterwards".
W.H. Könemann, in his Foreword to Good Laboratory and Clinical Practices, (P.A. Carson and
N.J. Dent, editors) Butterworth Heinemann, Oxford, 1990
GLP is a philosophy of laboratory practice and management which is dedicated to doing things correctly.
Principles of GLP are applied in regulations to which many laboratories comply.
It is up to individual laboratories to specify their own GLP procedures. However, instrument manufacturers
can help. The Sirius GLpH system for pH measurement has been designed to help its users to apply
principles of good laboratory practice during the measurement of pH. GLpH will measure pH correctly, keep
on measuring it correctly, and give users the data they need to prove that it was measured correctly.
The use of automation ensures that GLpH will keep on measuring pH correctly day-after-day, and that all
users of GLpH will obtain similar results for a given sample.
Measuring pH correctly calls for carefully defined procedures to be followed. These procedures include
careful handling of solutions and analytical hardware, observation and record-keeping, paying particular
attention to the issues shown in Table 2. These procedures are used in SOPs (Standard Operating
Procedures) for pH measurement.
14
Issue
What GLpH does...
Using traceable buffer solutions
•
recognises five buffers whose formulae are
agreed by NIST, DIN and BS.
Changing the buffers regularly
•
reminds users to change buffers at
pre-programmed times or after userprogrammed number of measurements
Calibrating carefully and often
•
calibrates automatically at pre-programmed
times of day or after user-programmed
number of measurements
Accounting for temperature effects
•
•
temperature compensation for slope change
applies correct pH of buffer at any
temperature
operator can calibrate temperature probe
•
Monitoring electrode performance and
condition
•
•
•
stores 250 calibration results
stores 550 days of hourly mV in pH7 buffer
warns user the moment that system
deviates from programmed specification
Re-filling the electrode regularly
•
reminds user to refill the electrode
Following a reproducible
measurement protocol for each
sample
•
pre-programmed Methods of measurement
are applied without change sample-aftersample
Manual intervention is logged as a deviation
from GLP
•
Moving the electrode between
solutions
•
movement of electrode is automated
Stirring, taking pH readings at
equilibrium
•
these functions are automated
Recording the results
•
•
results are printed
stores 850 pH measurement results
Cleaning electrode between samples
•
electrode cleaning is automated
Monitoring for abnormal events
•
user is warned of all deviations from
programmed procedures
Responding to requests for audits
•
•
all experimental data is stored.
audit trail logs are printed for all user
maintenance operations
Table 2. How GLpH handles issues of GLP
3.2. Testing of instruments and components
Each GLpH instrument is manufactured to a high standard and tested before shipment to the customer.
Electrodes and temperature probes sold by Sirius for use with GLpH, as well as all electronic assemblies
within GLpH are marked with serial numbers for traceability to source. Every electrode is tested for response
in three buffer solutions before shipment.
GLpH complies with the appropriate European regulations on electro-magnetic emissions and interference,
and carries a CE mark.
15
3.3 Testing and validation of software
GLpH uses software to control the automation and measurement. To allow users to comply with regulations,
Sirius are willing to provide access to GLpH software documentation, provided users agree to sign a
confidentiality agreement. There will be a charge for this service.
The software is developed in modular units and tested in stages with many examples. The results from these
tests are compared against results gained from standardized procedures. When the software is frozen at a
given revision, copies of all source code and relevant files are copied to floppy disk. Two copies of this are
kept, one on site at Sirius, and the other off site.
If it is deemed necessary to alter the software for enhancement or bug fixes, the relevant changes are
discussed in advance and implemented, with a comment record added to the relevant areas of the source
code. The software revision goes through beta testing for a relevant period of time, suitable for the size of
the change made.
Software features are tested with standardized procedures that should return given values. The results from
these tests are used to refine the source code to give optimal results in all cases. Software under test is run
by several users from different perspectives.
Date and time of acquisition are recorded alongside each item of raw data as it is acquired. Stored
calibration and sample results data cannot be changed within GLpH. Data can be downloaded to an external
device, but amended data cannot be re-loaded into GLpH.
Use of Personal log-on IDs and password are required for certain operations in GLpH.
3.4 Installation Qualification and Operational Qualification (IQ and OQ)
Installation Qualification (IQ) and Operational Qualification (OQ) procedures for GLpH users are published in
this instruction manual (see Sections 4.3 to 4.7)
16
4. Setting up GLpH
4.1 Overview
Figure 9 shows a fully-assembled GLpH Autosampler (Version 2 Hardware) with all major parts identified.
GLpH Single-Sample (Version 1 Hardware) is shown in Figure 10.
Figure 9. GLpH with autosampler
Figure 10. GLpH single sample version
GLpH holds two bottles containing water for washing the probes and a bottle containing a special wash
solution such as a detergent solution, and up to six vials containing calibration buffer solutions in the vial
locating plate. Buffer solutions can also be placed in the autosampler tray. It uses three probes (a glass pH
electrode, stirrer and Pt100 temperature probe), which it lifts automatically and places into calibration buffer
solutions, wash solutions and sample solutions.
17
During normal operation of GLpH, users do not need to touch the electrode or other probes.
GLpH is controlled via the keypad or via a plug-in computer keyboard (supplied as standard with
autosampler). Instructions are displayed on a 16-line, 40-column liquid crystal display screen. Results of
calibrations and measurements are displayed on the screen. They can be printed if a suitable serial printer is
connected. They are also saved in memory. Saved results may be inspected at any time on the display, or
downloaded to an external data capture device such as a PC.
GLpH is controlled by built-in software, which provides many features to help users who want to be sure that
pH is being measured in accordance with GLP procedures.
For the autosampler, there is a choice of a 32 or 50 position tray, with or without temperature control. GLpH
single-sample instruments with version 1 hardware must be modified before the autosampler can be
connected. An autosampler conversion kit and software upgrade kit are available to customers who would
like to upgrade to the autosampler version.
4.2 Electrical connections
All electrical connections are made to the side panel on the left of GLpH, as shown in Figure 11.
In single-sample GLpH, the connector marked ‘computer keyboard’ connects to a keyboard. In the
autosampler GLpH, it connects to the autosampler unit.
Figure 11. GLpH electrical connections
18
4.3 Packing checklist
GLpH single-sample instruments and autosamplers are packed in separate boxes. The boxes should contain
the following items. Please identify all parts when unpacking. To fulfil Installation Qualification (IQ)
procedures, users may tick the boxes below to confirm each part as it is unpacked.
9
9
Single-sample
Autosampler
GLpH base unit
Autosampler
Top cover (attached to base unit)
Ribbon cable GLpH Æ autosampler
Hexagon (Allen) key
Keyboard connector cable GLpH Æ autosampler
Side cover plate (attached to base unit)
Dust cover
Tower
Tray (ordered separately)
Four screws to attach tower (attached to tower
base plate)
Vials for tray
Electrode holder
External water connectors
Stirrer, with stirrer paddle attached
Temperature probe
pH electrode
Filling solution for pH electrode
Cable sheath
Locating plate for calibration vials
Six calibration vials
Three wash solution beakers
Sample beaker station
Mains lead
Instruction manual
4.4 Setting up GLpH hardware for the first time
DO NOT PUT ANYTHING ON TOP OF GLpH WHERE IT MAY BE KNOCKED OFF BY THE MOVING
TOWER.
Follow these instructions step-by step. To fulfil Installation Qualification (IQ) procedures, users may tick the
boxes next to each number to confirm each step during setup.
19
4.4.1 Setting up GLpH single-sample version
Tools required: screwdriver with Phillips head, 2mm Allen key
1.
Prepare a suitable bench space for GLpH. You will need a space at least 600mm (24") wide and
450mm (18") front-to-back, with at least 470mm (19") height.
You will need one electrical socket (110V to 240V AC) for GLpH, and additional electrical sockets if
you are using a printer or a computer connected to GLpH.
2.
Unpack GLpH and check the contents of the packaging. (See checklist, Section 3.3).
3.
Place the GLpH base unit on the bench.
4.
Unscrew the two hexagon (Allen) bolts which are used to attach the top cover.
5.
Remove the top cover and Allen bolts and place to one side.
6.
Attach the tower to the tower base plate using the four screws provided. Tighten the screws firmly.
7.
Plug in the lead to make the electrical attachment between the tower and the tower base plate.
8.
Manually move the tower from side to side to check that it is running freely.
9.
Re-attach the top cover.
10. Attach the electrode holder to the electrode holder arm. Loosen the thumb screw on the electrode
holder. Locate the electrode holder over the two stainless steel pins on the electrode holder arm.
Push the electrode holder fully on to the two pins. Tighten the thumb screw until it locks the electrode
holder in position. NOTE: the head of the thumb screw must face towards the tower.
11. Pour distilled or deionised water into the two water wash beakers and place them in wash positions 1
and 2 on GLpH. Pour distilled or deionised water into the special wash beaker and place in position.
The special wash beaker may be filled with a special wash solution if desired (see Section 6.5).
12. Place the temperature probe into the electrode holder. Push it down as far as it will go. Write down
the Serial Number of the temperature probe.
13. Carefully remove the soaking bottle from the tip of the electrode and gently wipe the electrode dry.
Keeping well away from any hard surfaces, gently shake the electrode like a clinical thermometer to
remove any air bubbles. Remove the cap covering the fill arm.
14. Place the pH electrode into the electrode holder. Push the electrode cap down as far as it will go into
the holder. The fill hole should face towards the front. Write down the Serial Number of the pH
electrode (written on the electrode copy)
15. Top up the electrode with the filling solution provided.
16. Place the stirrer (with stirrer paddle attached) into the electrode holder. Push it down as far as it will
go.
17. Attach the cable sheath. See Section 4.5.
18. Move the electrode arm, with probes attached, and manually lower the probes into the water wash
beaker no.1.
19. Place the sample beaker station on to its location studs. Push it down to ensure it correctly fitted.
20. If you are using a computer keyboard, plug it into GLpH (see Section 10.2).
20
21. If you are using a printer, check that you have the correct cable to connect it to GLpH (see GLpH
instruction manual, Section 11.1.6)
22. Decide which buffer solutions you want to use (see Section 5.4). Pour the buffer solutions into the
calibration buffer vials leaving 1 to 2cm unfilled, and place the vials into GLpH (see Section 5.3). The
left-hand vials (no. 1 and 2) must contain pH7 or pH6.86 buffer.
23. Turn on power to the printer (if connected) and switch it on-line.
24. Turn on power to GLpH. The instrument will go through an automated initialisation routine. GLpH will
lift the electrode arm fully and move the tower all the way to the left to check its home position. It will
then move to the two water wash solutions and into the left-hand pH7 buffer solution, displaying the
message “System Initialisation in progress”. Watch it carefully to ensure free running. After the
initialisation routine is complete it will display the Supervisor menu (Figure 12) if the instrument is
new and un-programmed, or the Normal User menu (Figure 13) if it has been previously used.
25. Assemble the printer, select the correct communications settings (from the Supervisor menu, select
Setup/System setup/Serial port connected to then use LESS / MORE to select the appropriate
setting) and connect it to the GLpH (see GLpH instruction manual, Section 11.1).
Figure 12. Supervisor menu, single sample version
Figure 13. Normal user menu, single sample version
4.4.2 Setting up the GLpH and autosampler
1.
Prepare a suitable bench space. For the autosampler version, you will need a space at least 700mm
(28"), 600mm (24") front-to-back and 560mm (22") high.
2.
Unpack the autosampler and check the contents of
the packaging (See checklist, Section 4.3)
3.
Place the autosampler base unit on the bench.
4.
Connect the plug on the ribbon cable marked autosampler to the socket on the side of the
21
autosampler, as shown in Figure 14.
Figure 14. Autosampler connections
Figure 15. Position of ribbon cable connecting GLpH base unit to autosampler
5.
Lay out the ribbon cable on top of the autosampler as shown in Figure 15.
6.
Set up GLpH as described in Section 4.4.1, 2-18.
7.
Remove the side cover plate from GLpH. This is not required when GLpH is used with an
autosampler. To remove the side cover plate, slide it to the right off the four studs which hold it in
place. No tools are required. See Section 6.3 for instructions.
8.
Connect the plug on the ribbon cable marked GLpH to the socket on the under-side of GLpH, then
place GLpH on top of the autosampler, with its four rubber feet located in the four circular holes on
the top of the autosampler. Make sure the ribbon cable lies as flat as possible, and is not trapped
underneath the feet of GLpH.
9.
Connect the keyboard cable as shown in Figure 14.
10. Place the autosampler tray on the tray base plate.
If it is a temperature-controlled tray, connect the water tubes to the connectors on the side of the
tray.
The connector on the left-hand side (labelled B) must be connected to the bottom connector on the
tray.
The connector on the right-hand side (labelled T) must be connected to the top connector on the
tray.
If temperature control is required, connect a controlled-temperature water circulator to the external
connectors on the right hand side of the autosampler.
22
11. Complete the set up of GLpH as described in Section 4.4.1, 21-24.
12. Turn on power to GLpH. The instrument will go through an automated initialisation routine. The
autosampler tray will move fully forward. GLpH will lift the electrode arm fully and move the tower all
the way to the left to check its home position. It will then move to the two water wash solutions and
into the left-hand pH7 buffer solution, displaying the message “System Initialisation in progress”.
Watch it carefully to ensure free running. After the initialisation routine is complete it will display the
Supervisor menu (Figure 15) if the instrument is new and un-programmed, or the Normal User menu
(Figure 16) if it has been previously used.
Figure 16. Supervisor menu, autosampler version
Figure 17. Normal user menu, autosampler version
4.5 Installing the cable sheath
Use these instructions when installing probes in GLpH for the first time, or when removing or replacing
individual probes.
4.5.1 New probes
1.
If you are installing new probes, place the three probes into the electrode holder in this order:
1. temperature probe
2. pH electrode
3. stirrer
2.
Stand in front of GLpH and gather the three cables together in your hands.
3.
Hold the cable sheath in one hand and the cables in the other hand. Using a thumb, carefully feed
the stirrer cable into the slot which runs the length of the cable sheath. A special knack is required to
feed the cable into the slot, but it is easily learned!
4.
Feed the other two cables into the slot.
5.
When the three cables are inside the cable sheath, slide the sheath over the cables until about 2cm
of each cable (measured to the furthest ends of the plugs) is sticking out of the end of the sheath.
23
6.
7.
Plug in the three cables to GLpH.
The two plastic clips which hold the cable sheath in place can be found on the left-hand side of the
instrument and on the back of the tower. Carefully open the clips and place the cable sheath inside.
Allow approximately 16cm between the connectors and the lower clip, and about 23cm between the
clip on the tower and the end of the cable sheath. Snap the clips closed.
Figure 18. Installing the cable sheath
8.
Move the electrode holder fully up and down by hand above the sample position to ensure free
running. Then move it back to the pH7 storage solution, again checking for free running. If
necessary, adjust the position of the cables in the clips.
9.
Ensure that the electrode is in the pH7 storage solution, then switch on GLpH, or press any key to
re-enable automation.
4.5.2 Replacing probes
1.
Turn off GLpH, or disable automation from the Supervisor maintenance menu, or pressing YES to
install a new electrode from Setup/Install electrode, electrode parameters.
2.
By hand, lift the electrode holder, move the tower, and lower the electrode holder when it is in the
sample position. Installing cables while in this position ensures that they will reach over the entire
distance of travel.
3.
If probes are currently installed, unplug all probes and unfasten the two clips which hold the cable
sheath in place. Take care not to damage the clips: use two hands to unclip. Remove the cable
sheath from the cables.
4.
To replace a pH electrode, first remove the stirrer from the electrode holder. Then remove the old pH
electrode. Place the new pH electrode in the electrode holder with the fill hole facing forwards. Then
replace the stirrer in the electrode holder.
4.6 Setting up GLpH for the first time
These instructions tell you how to set up the GLpH program for the first time, using default settings. We
suggest that you set up GLpH this way to get started. You can change the settings later as you gain
experience.
Abbreviated programming instructions are printed in bold, e.g. Setup/Setup system means “Press MORE or
LESS to select Setup from the Supervisor menu, then press YES, then press DOWN to select Setup
System, then press YES”.
1.
Familiarise yourself with the operation of the keypad and display (see Section 10).
2.
Check the time and date. From the Supervisor Menu, select Setup/Setup time and date. Follow the
instructions displayed. (GLpH is normally supplied with UK time set up).
3.
Install the pH electrode. Select Setup/Install electrode, electrode parameters. Enter the serial
24
numbers of the electrode and temperature probe. Default parameters for calibration suspect and fail
are shown in Figure 19.
4.
From the Supervisor Menu, select Setup. Set up your preferred settings. See GLpH instruction
manual, Section 8.1 for full setup instructions.
Figure 19. Install electrode display
5.
Press the CAL NOW button to do an automatic calibration
6.
After calibration, GLpH is ready for use by one of the four factory-set default methods.
4.7 Operational Qualification
This section describes an Operational Qualification (OQ) procedure which users of GLpH can follow to
confirm that the instrument functions as specified and operates correctly. Before undertaking this test, place
GLpH in a clean, dry environment where the room temperature is reasonably constant and where it will not
be disturbed by unauthorised persons. Preferably, also attach a printer and leave it on-line.
1.
Set up GLpH with a pH electrode which is known to be in good condition. Install fresh wash
solutions. Install fresh buffer solutions according to your preferred protocol (from the Supervisor
menu, select Setup/Set calibration protocol). Protocol 3 is recommended along with Orion buffer
solutions.
2.
Check that the temperature probe is reading temperature correctly and recalibrate the temperature
probe if necessary. Follow the procedure in Section 12.5.2.
3.
Set up GLpH to calibrate automatically at 15 minute intervals. From the Supervisor menu, select
Setup/Setup actions and reminders. Automatic Electrode Calibration should be highlighted,
press YES. Action status should be highlighted, make sure that this is set to Enabled (press LESS
/ MORE keys to change). Press DOWN to highlight Action mode. Make sure that this is set to Time
period (press LESS / MORE keys to change). Press DOWN. Use LESS / MORE keys to change
Daily Period to 0, Hours Period to 0, and Minutes Period to 15. At the bottom of the screen should
be displayed “Next in 0 days, 0 hours and 15 minutes”. Press ESC.
Disable all other automatic actions and reminders during this test. From the Supervisor menu, select
Setup/Setup actions and reminders. Automatic Electrode Calibration should be highlighted,
press DOWN to highlight Install fresh wash solutions, then press YES. Action status should be
highlighted, make sure that this is set to Disabled (press LESS / MORE keys to change). Press
ESC. Repeat for Install fresh pH buffer solutions, Refill electrode with filling solution, and
Order new Reagents / Consumables.
Set up the electrode parameters according to those recommended in Figure 19. NOTE: users may
set their own specifications for these parameters as required. From the Supervisor menu, select
Setup/Install electrode, electrode parameters. Install a new electrode will be highlighted, press
DOWN to select the above 100% slope suspect parameter. Use LESS / MORE keys to change the
value. Press DOWN to select the below 100% slope suspect parameter. Use LESS / MORE keys to
change the value. Repeat for the rest of the parameters. Press ESC.
25
4.
Press CAL NOW. Verify that the following operations were carried out:

Electrode was raised and lowered without problems
Tower moved between positions without problems
Stirrer switched on and off and stirred without problems
5.
Leave GLpH unattended for at least 1 hour so that it calibrates automatically 4 times, preferably
leave for 2 hours to calibrate 8 times.
6.
From the Supervisor menu, select Audit/Calibration history data and examine the calibration
history for the last 4 (or 8) calibrations. If all of the slope and E0 values are within the ranges
specified in Figure 19, and none of the printouts show that any points were taken after a stability
timeout (180 secs) or other warning message, GLpH has passed the first stage of OQ. Warning
flags are not displayed in the Calibration history data screen but are shown if the calibration log is
printed or as a code when the data is uploaded to a PC (see Section 11.2.9).
Single-sample version. Prepare three 150mL beakers containing 100mL samples of the three
calibration buffer solutions.
7.
8.
Place each sample buffer in the sample position and measure the pH three times consecutively
using the factory-set default Method 2: Default by stability, thin (see Figure 27 for method details).
From the Supervisor menu keep pressing ESC until the Normal user menu is displayed. Use UP /
DOWN to select the required method, then press YES. Place the beaker in the sample position, with
the centre of the beaker placed as closely as possible over the star-shaped target marked on the
sample beaker station. Press YES to start the pH measurement, then enter the sample ID and user
name.
From the Supervisor menu, select Audit/Sample results data and examine the sample results. The
flag is a symbol which indicates that the measurement was out-of-range, or that conditions during the
measurement deviated from GLP (see Table 5, page 52 for meanings of flag symbols). If the
variation between readings is less than +/-0.005pH units in each buffer solution, and none of the
readings was taken after a stability timeout (180 secs) or other warning flag, GLpH has passed the
second and final stage of OQ.
9.
If GLpH fails any of the tests above, check the system thoroughly and try again.
10. Autosampler version. Prepare three sample vials containing samples of the three calibration buffer
solutions.
11. Place the vials in autosampler positions 6, 19 and 32 (32 position tray) or 12, 29 and 50 (50 position
tray). Measure the pH three times consecutively using the factory-set default Method 2 (Default by
stability, thin). From the Supervisor menu keep pressing ESC until the Normal user menu is
displayed. Press YES to set up the autosampler tray. Select a position on the graphical display using
UP / DOWN / LESS / MORE on the keypad or the arrow keys on the keyboard, then setting up a
measurement in that position. Highlight a position on the tray, press YES, then enter the method,
sample ID, and user name. Place the vials in the sample positions. Press F2 or TAKE RESULT
when tray setup is complete.
From the Supervisor menu, select Audit/Sample results data and examine the sample results. The
flag is a symbol which indicates that the measurement was out-of-range, or that conditions during the
measurement deviated from GLP (see Table 5, page 52 for meanings of flag symbols). If the
variation between readings is less than +/-0.005pH units in each buffer solution, and none of the
readings was taken after a stability timeout (180 secs) or other warning message, GLpH has passed
the second and final stage of OQ.
12. If GLpH fails any of the tests above, check the system thoroughly and try again.
26
5. Calibrating GLpH
5.1 Why calibrate?
When placed in a solution, pH electrodes generate a voltage. The value of this voltage is related to the pH of
the solution. GLpH measures this voltage and uses the value to calculate pH. The voltage tends to drift
slowly with time, mainly as a result of small physical changes in the electrode. By calibrating, the effects of
this drift are minimised.
5.2 Overview of GLpH calibration
pH electrodes on GLpH are calibrated using buffer solutions. Up to five buffers may be used, chosen from
fifteen different Calibration Protocols. One of the buffer solutions must be pH6.86 or pH7. Calibration is a
fully automated procedure. It may be initiated manually by pressing CAL NOW, automatically at regular time
intervals or after a set number of measurements if this has been specified during Setup/System setup.
Buffer solutions are placed in calibration vials, which are placed in the vial locating plate, or in the
autosampler tray (if fitted). Two vials of each buffer are normally used. The left-hand vial is used for
washing the electrode with buffer; the right-hand vial for calibration. An exception to this is where more than
three different buffers are selected in a calibration protocol on the GLpH single-sample version. In this case,
only one vial of each buffer is used for the calibration. For the GLpH autosampler version, if more than six
vials are needed for a calibration the extra vials are placed in the autosampler tray. When GLpH is idle, the
electrode is stored in the left-hand pH6.86 or pH7 vial.
After calibration, GLpH calculates slopes (normalised to 25°C) and E0 values for the electrode, and saves the
results in the Audit file. Calibration results will be printed if printing has been requested. Warning messages
are displayed if calibration is out-of-range.
In addition to calibration, GLpH checks E0 (the mV reading in the pH7 storage buffer solution) once per hour.
Results are saved in the audit file. Warning messages are displayed if this mV reading goes out of range.
5.3 Changing the calibration buffers
Calibration buffer vials (Figure 20) should be refilled daily with fresh buffer solutions. As a guide, pH1.68, 4,
6.86, 7 and 9.18 solutions are stable in air for about one day. pH10 solutions start to degrade by absorbing
atmospheric CO2 after about eight hours of use.
Figure 20. Six calibration vials showing possible setup for various calibration positions
To ensure GLP, buffers should only be changed while GLpH is switched on, in response to a reminder, or
else on demand by using the Maintenance menu.
Before changing calibration buffers, make sure that the water wash solutions are clean and fresh.
27
To change buffer solutions on demand, press NO while the Normal User menu or the Supervisor menu is
displayed to call up the Maintenance menu. Select Change Calibration Buffers and press YES...
To change buffer solutions in response to a reminder, press YES in response to the flashing Reminder
due....
...a message similar to the example in Figure 21 will be displayed. Press YES.
Figure 21. Installing fresh calibration buffers in response to a calibration
protocol change. The display is from an autosampler GLpH. In single sample
versions, a view of the tray is not shown on the right-hand side.
The electrode will lift out of the pH7 storage position and lower into the 1st water wash position. Empty the
vials and refill with fresh buffer solution. Alternatively, to conserve buffer solution, move each of the
calibration vials one position to the left so that they become wash vials. Empty the wash vials and refill with
fresh buffer solution, leaving the top 2cm of the vial unfilled, then place them in the calibration position.
Press YES when the refilled vials have been replaced in their correct positions. The electrode will move into
water wash 2, then into the pH7 storage position. An audit trail log will be printed if it has been requested in
Setup/System Setup.
An automatic reminder to change the buffer solutions and wash solutions at regular intervals, or after a user
programmed number of tests, can be set up by selecting Setup/Setup actions and reminders from the
Supervisor menu.
28
5.4 Calibration protocols
A choice may be made from fifteen calibration protocols (see Table 3).
To create a new protocol use Setup/Set calibration protocol from the Supervisor menu. Highlight the next
number which has no protocol defined and press CAL NOW. A display like Figure 22 will appear. No buffer
will be highlighted. Press YES and then use UP or DOWN to select the buffer you want from the list (Figure
23). Repeat for up to five buffers. Vials 1 and 2 must contain pH7 or pH6.86 buffer. Use
UP/DOWN/MORE/LESS and YES to set calibration positions and wash (optional) for each buffer.
pH value of buffer solution (vials numbered from left to right)
protocol
no.
Vial 1
storage/wash
Vial 2
calibration
Vial 3
wash
Vial 4
calibration
Vial 5
wash
Vial 6
calibration
1
7†
7†
4
4
not used
not used
2
7†
7†
not used
not used
10
10
3
7†
7†
4
4
10
10
4
7†
7†
not used
not used
9.18
9.18
5
7†
7†
4
4
9.18
9.18
6
7†
7†
1.68
1.68
not used
not used
7
7†
7†
1.68
1.68
10
10
8
7†
7†
1.68
1.68
9.18
9.18
9 - 15*
No protocols pre-set. New protocols may be defined by user.
Table 3. Calibration protocols.
† or 6.86 if calibration protocol modified. Asterisk (*) will be shown if protocol incomplete
Figure 22. Creating and editing calibration protocol, autosampler version
29
Figure 23. Creating and editing calibration protocol, buffer selection
5.5 Choice of buffer solutions
Buffer solutions suitable for pH electrode calibration are specified in various international standards. GLpH
has been designed for use with five selected NIST (formerly NBS, USA), DIN (German) and BS (British)
standard buffer solutions (Table 4), and a commonly-used pH7 buffer solution which is not a recognised
standard. There are moves to unify the specification of buffer solutions in Europe under a new ISO
(International) standard. The relevant standards are:
NIST: buffers are specified by R.G. Bates in Journal of Research of the National Bureau of Standards,
Vol.66A, 1962, page 179
DIN
19266
BS:
6068: Part 2: Section 2.50 (1995)
ISO
10523
Buffer
NIST
DIN
BS
formula
pH 1.68
_
_
pH4
_
_
_
0.05mol potassium hydrogen phthalate/kg water
pH7
see below
pH9.18
_
_
_
0.01mol sodium tetraborate decahydrate/kg water
pH10
_
0.05mol
water
potassium
tetraoxalate
dihydrate/kg
_
1:1 mixture of sodium carbonate and sodium
hydrogen carbonate (each 0.025mol/kg)
Table 4. GLpH buffer solutions.
5.6 pH 7 buffers
GLpH recognises two alternative formulae of pH7 buffer solutions.
The “nominal” formula contains a mixture of phosphate salts (disodium hydrogen phosphate and potassium
dihydrogen phosphate) plus preservatives, and it has a pH value of 7.000 at 25°C. Buffers of this type are
supplied by several manufacturers. However, the nominal formula is not accepted by any international
standard.
The “standard” formula (approved by NIST, DIN and BS) has a pH value of 6.865 at 25°C. The solution is a
1:1 mixture of disodium hydrogen phosphate dihydrate and potassium dihydrogen phosphate (each
0.025mol/kg).
If you decide to use pH6.86 buffer use Setup/Set calibration protocol from the Supervisor menu to specify
your choice. Highlight the protocol you want to change then press CAL NOW. Highlight pH7 then press
YES. Use UP to select pH6.86 from the list then press YES.
30
5.6.1 Using other buffers
GLpH can support up to ten new buffers in addition to the six buffers already programmed. To add a new
buffer to the list use Setup/Set calibration protocol from the Supervisor menu to create a new protocol as
described above. Instead of selecting an existing buffer, highlight <New>. Press YES and enter the pH of
the new buffer at 25ºC. You must then enter coefficients A0 - A3 (if available) to support the calculation of a
temperature/pH profile of the buffer by curve-fitting. A typical buffer profile is shown in Figure 24. If you do
not know a value for A0 and the other temperature coefficients (A1, A2 A3), enter A0 = buffer pH value at
25ºC, and A1, A2, A3 = 0.000. To review the temperature coefficients of one of the built-in buffers, highlight
the buffer value shown in Figure 23, then press CAL_NOW. To enter a very low value for a coefficient (e.g.
7.000000e-7), enter 0.0000007, then press YES.
See Section 2.6.3 for further guidance on
buffer/temperature profiles.
Figure 24. Create/edit buffer pH profile
5.7 During and after calibration...
During calibration, a screen like Figure 25 will be displayed while the electrode is in the calibration buffer.
The reading in each buffer is taken automatically when it has satisfied the built-in stability criteria, or when
the stability timeout countdown has reached 0 seconds. Note that users cannot amend the built-in stability
criteria which apply during calibration. A reading may be taken manually by pressing TAKE RESULT; this will
over-ride the stability and timeout criteria. Results obtained after timeout or taken manually are “flagged” in
the audit file of calibration data. After calibration, results are added to the Audit file. Results will be printed
after each calibration if Print Calibration log has been selected in Setup/Setup system. A typical printout is
shown in Figure 26. GLpH can be set up to lock on failure of a calibration, or if the calibration becomes
suspect, so that no analysis can be performed. See Sections 8.1.4 and 8.1.5.
Figure 25. Calibration in progress
31
Figure 26. Example of calibration log
32
6. Measuring pH
6.1. Measuring pH with single-sample version
1.
From the Supervisor menu, continue pressing ESC until the Normal User menu is displayed (see
Figure 13).
2.
Use UP and DOWN to select the method which is most suitable for your sample. Then press YES.
3.
Pour sample into a suitable beaker. Make sure there is sufficient depth of sample in the beaker such
that the liquid junction of the pH electrode will be fully immersed At least 1cm depth of immersion will
be required.
NOTE: Follow the instructions for measuring large and small samples in Sections 6.3 and 6.4 if the diameter
of your beaker is larger than 1 litre capacity, or is small in diameter.
4.
Place the beaker in the sample position, with the centre of the beaker placed as closely as possible
over the star-shaped target marked on the sample beaker station. Press YES to start the pH
measurement.
5.
GLpH will ask some questions before starting the measurement. Depending on how GLpH is set up,
it will ask for sample ID, User ID and user PIN number. Answer these questions correctly. After you
have answered, the electrode will be lifted out of the pH7 storage solution, washed in two water
washes, and lowered into the sample. (Some methods specify Detach Electrodes before
measurement, or for manual lowering, with height Set at Test).
6.
Pressing MORE or LESS while the electrode is in a sample will change the remaining time during
timed operations. Pressing UP or DOWN while the electrode is in a sample will increase or
decrease the stirrer speed. These operations represent deviations from GLP and will be ‘flagged’.
7.
GLpH will take a pH reading when the timed reading or stability criteria specified in the method have
been satisfied. pH will be measured and displayed, and printed if a printer is connected and printing
has been requested. The last pH result taken will remain displayed on the screen until another
sample measurement is initiated. The result will also be shown on the main menu screen. If stability
criteria are not satisfied the result will be taken automatically when the stability timeout countdown
has reached 0 seconds. A reading may be taken manually by pressing TAKE RESULT; this will
override the stability and timeout criteria. Results obtained after timeout or taken manually are
‘flagged’ in the saved record of calibration data.
8.
After measurement the electrode will be raised from the sample and washed in two water washes
(preceded by a special wash, if defined in the method), then moved over the sample position, where
it will wait 60 seconds for a new sample. If no new sample is placed in position after 60 seconds it
will park the electrode in pH7 buffer solution.
6.2. Measuring pH with autosampler version of GLpH
1.
From the Supervisor menu, continue pressing ESC until the Normal user menu is displayed (see
Figure 17).
2.
Press YES to set up the autosampler tray. Select a position on the graphical display using
UP/DOWN/LESS/MORE on the keypad or the arrow keys on the keyboard, then setting up a
measurement in that position. Highlight a position on the tray, press YES, then enter the method,
sample ID, and user name. Measurements can be set up in four different ways.
a. Use F10 to restore the details of the last autosampler tray run.
33
b. Set up each measurement position-by-position.
c. Use F1 to repeat the details of the last measurement set up.
d. Batch setup mode. Press YES to set up autosampler tray. Place cursor in the first position, then press
F4. Use MORE and DOWN to highlight all the positions in the tray where you want to place vials. When
they are highlighted, press YES. GLpH will ask:
Sample ID:
Method:
User name:
Enter the ID of the first sample you want to measure, i.e. the sample in the lowest-numbered tray position.
Enter the method and user name, and press YES. This method and user name will be used for all the
samples in the tray. GLpH will ask for the next sample ID. Enter it and press YES. Continue until you have
entered all the sample IDs.
3.
Pour samples into vials. Make sure there is sufficient depth of sample in the vial such that the liquid
junction of the pH electrode will be fully immersed. At least 1cm depth of immersion will be required.
4.
Place the vials in the sample positions. Press F2 or TAKE RESULT when tray setup is complete.
5.
The electrode will be lifted out of the pH7 storage position, washed in two water washes, and
lowered into the sample.
6.
Pressing MORE or LESS while the electrode is in a sample will change the remaining time during
timed operations. Pressing UP or DOWN while the electrode is in a sample will increase or
decrease the stirrer speed. These operations represent deviations from GLP and will be ‘flagged’.
7.
GLpH will take a pH reading when the timed reading or stability criteria specified in the method have
been satisfied. pH will be measured and displayed, and printed if a printer is connected. The last
pH result taken will remain displayed on the screen until another sample measurement is initiated.
The result will also be shown on the main menu screen. If stability criteria are not satisfied the result
will be taken automatically when the stability timeout countdown has reached 0 seconds. A reading
may be taken manually by pressing TAKE RESULT; this will override the stability and timeout
criteria. Results obtained after timeout or taken manually are ‘flagged’ in the saved record of
calibration data.
8.
After measurement the electrode will be raised from the sample and washed in two water washes
(preceded by a special wash, if defined in the method), then moved to the next sample position.
After the last measurement the electrode will return to the pH7 storage position after the wash
procedures.
9.
Any sample can be run in any position. Moving probes never pass over unmeasured samples.
10.
The system can be set up to prompt the last sample ID used when a tray is next set up and to
increment the sample ID if it ends with a number. Use Setup/System setup to select these options.
11.
Emergency samples. The system can be set up to allow for an emergency sample to be measured
after an autosampler run has been started. Use Setup/System setup to select this option. To interrupt a
sample run press CAL NOW or F1, then follow the instructions shown on the display.
6.3. Measuring pH in large beakers
This option is available in the single-sample version of GLpH only.
Beakers up to 10cm diameter and 14.5cm tall will fit on the sample beaker station. Most squat-form 1 litre
beakers can therefore be accommodated on GLpH.
Two options are provided for measuring samples in larger vessels.
34
For occasional measurements, the Detach electrodes option allows users to detach the electrode holder at
the time of measurement and move it by hand to any vessel placed close to GLpH. If you want to be able to
detach the electrodes, you must specify Detach electrodes, YES when writing a method.
During measurement with a method in which Detach electrodes has been specified, the electrode arm will
stop above the sample position, and the electrode arm will not be lowered. The message
Detach electrodes and place in sample
Press YES when ready to measure pH [XXX]
will be displayed while the time [XXX] counts down from 120 to 0 seconds.
Unclip the cable sheath from the clip at the back of the tower. Take care not to damage the clip: use two
hands to unclip. To detach the electrode holder from the electrode holder arm, loosen the thumb screw at
the rear of the electrode holder, and slide the electrode holder to the left until it is detached from the two
stainless steel pins. Move the electrode holder to the sample by hand, using a clamp as required to hold it in
place during measurement. Press YES when the electrode has been placed in the sample.
Automation is disabled while the electrode holder is detached, both by software and by an electrical
reed switch, which is activated magnetically while the holder is detached.
After measurement, re-attach the electrode holder to the electrode holder arm. Tighten the thumb screw.
Replace the cable sheath in the clip. Press YES to confirm the electrode holder has been re-attached.
If measurements are often required in large containers, it is possible to remove the side cover plate from
GLpH and raise the base unit above the bench level on a plinth (plinth not supplied). Vessels up to about
25cm diameter can then be placed in the sample position for automated measurement. The upper rim of the
beaker must be no higher than the top edge of the base unit.
Switch off GLpH or disable automation before removing the side cover plate.
To remove the side cover plate, turn GLpH around by 90º on the bench so that the display faces left. The
side cover plate should now face towards you. Pull GLpH towards you until the side cover plate is no longer
resting on the bench, but the main base unit is still resting on the bench.
Remove the sample beaker station.
Hold the cover plate in both hands by its sides. Press with the thumbs on to the end of the base unit until the
side cover plate is released from the four mounting studs. Remove the side cover station. Replace GLpH on
the bench.
When making automated measurements of samples in large vessels, make sure that the electrode liquid
junction is fully immersed in the sample.
6.4 Measuring pH using small vials
The electrode, stirrer and temperature probe normally fitted on GLpH will fit into vials with internal diameters
down to about 20mm. When using small-diameter vials, it is important the probes are lowered carefully and
accurately into the vials, so that all probes enter the vial, and no probes hit the vial and cause damage.
To measure pH in smaller vials, lift the temperature probe and stirrer in the electrode holder so that they are
about 1-2cm above the external liquid junction of the pH electrode. In this manner, the electrode can be
placed in a vial with a small diameter. Choose Set at test option to set electrode height manually at time of
assay. Select Setup/Temp probe in sample measurements and press NO to enter temperature manually.
During measurement with a method in which Set at test has been specified, the electrode arm will stop
above the sample position, and the electrode arm will not be lowered. The message
Use UP/DOWN to set electrode height [YES]
will be displayed.
35
Place the vial containing the sample in the sample position. Press DOWN to lower the electrode. Release
DOWN to stop the electrode. Press UP to raise the electrode. By this method the electrode can be carefully
lowered into the sample. Press YES to start measurement after the electrode is correctly immersed in the
sample.
6.5 Special wash solutions
Methods can be set up to include a special wash after pH measurement. The special wash precedes the
normal wash in water wash beakers 1 and 2. It is up to the user to formulate and prepare special wash
solutions.
Solutions of surfactants in water are useful for removing food and other samples which contain oils or fats.
At Sirius, we have used dilute solutions of Triton X-100 and of ordinary dishwashing detergents.
Solutions of water-miscible solvents in water (or in exceptional cases, the solvent alone) are useful for
removing more sticky deposits. Suitable water-miscible solvents include methanol, isopropyl alcohol and
ethanediol (ethylene glycol).When developing a method for a specific sample type, make sure that the
special wash is effective, and that all visible traces of the sample have been removed from the electrode,
stirrer and temperature probe by the time they leave the special wash. If necessary, stir for a longer time in
the special wash, or reformulate the solution to be more effective.
Do not use acids, bases or water-immiscible (e.g. toluene, xylene) solvents in the special wash beaker.
6.6 Special electrode clean
A special electrode clean is available in the Supervisor Maintenance menu. In this procedure, a beaker
containing a cleaning solution is placed in the sample position. GLpH lowers the electrode into this solution,
and leaves the electrode in the solution for a time specified by the user. When the electrode first enters the
sample the solution is stirred for five seconds. The stirrer is then turned off. Stirring may be re-activated and
adjusted manually by pressing UP and DOWN. After the special clean, the electrode is washed in water and
returned to the pH7 storage position.
A special electrode clean should be considered if the electrode response becomes slow or unstable.
Possible reasons include a blocked or partially blocked liquid junction, or an impervious, filmy deposit on the
glass membrane.
Suggested formulae for special cleaning solutions:
General cleaning: 30 minutes in 0.1M HNO3 or HCl, followed by two-hour soak in pH7 buffer.
Removing protein deposits: 60 minutes in 1% solution of pepsin in 0.1M HCl, followed by two-hour soak in
pH7 buffer.
Removing inorganic deposits: 60 minutes in 0.1M tetrasodium EDTA, followed by two-hour soak in pH7
buffer.
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7. Methods
7.1 Overview of automated pH measurement
GLpH measures pH by implementing instructions saved in Methods. Four factory-set default methods are
built in to GLpH. Additional Methods can be programmed by the operator.
Before each measurement, the operator must prepare the sample and place it in the correct position on the
sample beaker station or autosampler, and select the desired Method, then answer questions about the
sample and user IDs.
GLpH then moves the electrode, stirrer and temperature probe automatically into the sample and makes the
measurement according to the Method.
After measurement GLpH washes the electrode in the two water wash solutions, preceded by washing in the
special wash solution (if defined in the Method). GLpH single-sample version then waits for another sample,
but if another measurement is not started within 60 seconds, it automatically parks the electrode in the pH7
storage solution. Many options may be programmed into a method. These are described below.
7.2 Factory-set default methods
GLpH is supplied with four factory-set default methods, which are suitable for a wide variety of samples in
beakers ranging from about 50mL to 600mL capacity. The methods may require modification for use with
smaller or larger samples. A further 16 methods can be programmed. If required, the factory-set methods
can be over-written up to a total of 20 user-programmed methods. In addition to these four programmed
methods, GLpH contains one template method, which is discussed in Section 7.5.
The four default methods are shown in Figures 27 and 28.
37
Figure 27. Default methods for thin (i.e. non-viscous) samples. Left: by time. Right: by stability.
Figure 28. Default methods for thick (i.e. viscous) samples. Left: by time. Right: by stability.
38
7.3 Creating methods
To create a new method, select Method from the Setup menu, then choose Create a new method. If user
names are in use, GLpH will ask you to enter a user name (and PIN number if specified) before the method
is created. Pressing ESC will create the method with an “unidentified user”.
When a new method is created, GLpH displays a copy of the built-in Template method, which you can then
modify to suit your own requirements. The Template method is explained in Section 7.5. When a method is
created, it will be denoted as Rev 1 (revision ).
After you have created the method, press ESC. If a printer is connected and specified in System setup,
GLpH will print an audit trail log report to verify the method and operator details. It will also print the entire
method including the revision number.
7.4 Editing methods
To edit an existing method, select Method from the Setup menu, then choose Edit a saved method. A list of
all the defined methods is displayed. Select the method you want to edit. The method selected then appears
on the screen display. Users can then modify the method to suit their new requirements (see Section 7.5).
Each time a method is edited, it will be denoted with the latest revision number, e.g. Rev.2, Rev.3 etc.
After you have edited the method, press ESC.
If user names are in use, GLpH will ask you to enter a user name (and PIN number if specified) before the
edited method is saved. Pressing ESC will save the method with an unidentified user”.
If a printer is connected and specified in System setup, GLpH will then print an audit trail log report to verify
the method and operator details. It will also print the entire method including the revision number.
7.5 Step-by-step guide to methods
Entering the Method title
TEMPLATE SETTING: method number, followed by blank space
The first line at the top of the Method displays the method number (1 to 20), and is reserved for the title of
the method. To enter a title, press YES when this line is highlighted. Enter a title (up to 27 characters,
including spaces) using a computer keyboard (if connected) or using the built-in text entry pad. The text entry
pad is explained in Section 10.3.
Pre-stir time
TEMPLATE SETTING: 5 seconds
A pre-stir is a period of stirring which takes place before pH measurement begins. Its purpose is to
homogenise the sample and wet the electrode. However, viscous samples cannot easily be stirred without
cavitation, and a pre-stir may not be effective.
Suggested pre-stir settings
Thin (non-viscous) samples
Thick and viscous samples
5 seconds
0 seconds (no pre-stir)
Also set pre-stir to 0 seconds in conjunction
with no continuous stirring if you do not
wish to stir the sample at all
Samples containing suspended material
39
Consider using longer pre-stir times
Continuous stirring
TEMPLATE SETTING: NO
pH readings are generally more stable if samples are not stirred after the pre-stir. However, some SOPs call
for continuous stirring.
Sample consistency
TEMPLATE SETTING: Thin
Thin samples are non-viscous samples with water-like consistency which may be stirred rapidly on GLpH.
Thick samples are moderately viscous samples, for example tomato juice or water-based paint, which may
be stirred at normal speed on GLpH. If Thick is selected, the electrode will be once moved up and down
slowly after it has entered sample.
Viscous samples, for example tomato ketchup or mayonnaise, must be stirred at slow speed, or not stirred at
all. If Viscous is selected, electrode will be twice moved up and down slowly after it has entered sample. This
movement ensures that the electrode is properly wetted with sample.
If pre-stir and/or continuous stirring has been selected above, choice of sample consistency will cause GLpH
to recommend an appropriate default stirring speed.
Default stirrer speed
TEMPLATE SETTING: Normal speed
GLpH recommends stirrer speed according to the sample consistency.
Reading method
TEMPLATE SETTING: Stability
If reading by Stability is chosen, GLpH will take pH result when the stability criteria have been satisfied.
If reading by Time is chosen, GLpH will take pH result after a set time has elapsed. Functions not used in the
method are not displayed. For example, when reading by time is selected, stability criteria are not shown.
Reading by time after
If reading by time is chosen, 60 seconds will be proposed by GLpH. When developing a method, watch the
display to make sure that the pH reading is stable by the time GLpH takes the reading. For most samples,
readings are stable within 30 seconds.
Stability reading every
TEMPLATE SETTING: 0.2 seconds
This is the first of three stability criteria. GLpH takes one pH reading per unit of time selected. It calculates
the mean and standard deviation (SD) of the latest 10 consecutive readings. The SD is a numerical
indication of the rate of drift in the electrode reading, and it is used to determine the stability (see below).
Note: the SD value changes rapidly, and is not displayed.
Max pH drift per minute
TEMPLATE SETTING: 0.10000 ∆pH
This is the second of three stability criteria. The electrode reading usually drifts a lot when it is first placed in
a sample, so the SD of the mean of 10 pH readings is high. The SD value is re-scaled to units of pH units
per minute. GLpH takes a result when the drift has fallen to the value specified here.
40
Stability timeout after
This is the third of three stability criteria. If the pH reading never satisfies the first two stability criteria, the pH
result will be taken when the stability timeout is reached.
Sample Drip drop time
Some samples e.g. honey, printing ink, cling to the electrode after measurement, but they drip off if the
electrode is left standing in air. If a Drip drop time is specified, the electrode will be held in the air above the
sample beaker after measurement to allow the sample to drip. This minimises contamination of the wash
solutions. Not all samples drip! The Drip drop time for each sample should be decided by experiment.
HINT: during method development, try 10 seconds drip drop time. Watch for drips while the electrode is
above the sample after measurement. If it looks as if drips are developing, press MORE to increase the drip
drop time in 5-second steps.
Wash in special wash
The special wash beaker can be filled with a solvent or detergent solution to wash sticky samples off the
electrode after measurement. Select 0 seconds if special wash is not required. See Section 6.5 for
suggestions for special wash solution formulae.
Special wash to use
TEMPLATE SETTING: Wash name 1
The special wash solution name may be selected from any which have already been saved in the list of ten
special wash solutions in Setup/Enter special wash names. This option will only appear if a period of time is
entered for the special wash.
Wash in water wash 1 & 2 for
If the electrode carries solid or semi-solid materials into the final water wash 2, the life of the solution will be
reduced. Watch the electrode carefully during method development to make sure it is clean after washing.
The pH of water wash solutions is displayed during the wash. Consider changing the solutions if the pH
deviates outside the range 5 to 9.
Calibration pH buffers
TEMPLATE SETTING: When a new method is created, the calibration protocol which is currently in use will
be proposed.
Other buffers can be entered if required, or don’t care can be entered if you don’t care which buffers are
used. For some samples it is not important which calibration protocol was used. However, accuracy is
improved if alkaline samples are measured after calibration between pH7 and a high-pH buffer, and acidic
samples after calibration between pH7 and a low pH buffer. In single-sample instruments, if a calibration
protocol is specified in a method, GLpH will not allow measurement using the method to take place until a
calibration using the correct protocol has been done.
pH display resolution
TEMPLATE SETTING: 0.01 units
GLpH displays only the number of places specified in a method when measuring pH.
41
Monitor sample pH for
TEMPLATE SETTING: Disabled
If a time (e.g. 5 minutes) is entered, the electrode will remain in the sample for that time after the pH result
has been obtained. The pH will be continuously displayed so that the result can be monitored. Pressing NO
sets up the method so that the electrode remains in the sample indefinitely (until NO is pressed). This is a
useful feature if GLpH is used for making up buffer solutions.
pH print interval
TEMPLATE SETTING: Disabled
If a time (e.g. 30 seconds) is entered, GLpH will print a sample pH value every 30 seconds for as long as
sample pH is being monitored. This function is enabled only when sample pH is being monitored.
Detach electrodes (This option is only available on the single-sample version of GLpH).
TEMPLATE SETTING: NO
This feature is used when pH measurement is required in a large, oddly-shaped or fixed-position vessel that
cannot be placed in the normal sample position. If YES is selected, electrodes will wait above sample
position before pH measurement. You may remove the electrode holder containing the electrode, stirrer and
temperature probe and place them in any vessel, such as a large beaker placed next to GLpH. Automation is
disabled while the electrode holder is detached (see Section 6.3).
Move electrodes down
TEMPLATE SETTING: All the way
This feature is used to set the distance through which the electrode is automatically lowered into the sample
for pH measurement.
It is also used to enable manual lowering of the electrode before measurement; this would be useful for
aiming the electrode into a narrow sample container (see Section 6.4).
Options
All the way
Electrode will be automatically lowered all the way (140mm) into the sample
at the start of pH measurement.
Press LESS or MORE
Reduces or increases the programmed distance that the electrode will be
automatically lowered. The selected distance will be displayed.
Enter a height in mm
Electrode will be automatically lowered to the requested height.
Press NO
Option for height to be Set at Test.
Electrode will wait over the sample, and the operator must
press DOWN and UP to set the electrode position at the
start of each measurement.
Temperature range min and max
TEMPLATE SETTINGS: -10.000 and +110.000 ºC
The temperature minimum and maximum values may be set by the operator. Follow the instructions on the
screen display. A warning will be displayed, printed and saved if the temperature of a sample is outside this
programmed range during measurement.
42
Sample pH range min and max
TEMPLATE SETTINGS: -19.000 and +16.000 pH
The pH minimum and maximum values may be set by the operator. Follow the instructions on the screen
display. A warning will be displayed, printed and saved if the pH of a sample is outside this programmed
range during measurement.
Notes on out-of-range temperature and pH
Out-of-range conditions are indicated by:
•
•
•
•
Temperature and/or pH values appearing in reverse video (black on white) on the display
A beep as the final result is displayed
•
Statement on display that:
pH and/or temperature out of range!!
•
Statement on printout that:
pH and/or temperature out of range!!
Out-of-range condition displayed in Sample results data (see Section 9.2.5)
Out-of-range condition available in LIMS output of Sample results data
43
8. Setup
8.1 System Setup
This section explains each of the options available from Setup in the Supervisor menu. Pressing YES at the
Setup prompt displays the Setup Menu. The items in the Setup menu are reviewed below.
Figure 29. Setup menu
8.1.1 Setup/System setup/System Lock code
Two classes of GLpH users may be defined. Normal users are people who have received training on basic
operation of GLpH, but who do not need to set up the instrument, program methods or examine the audit
files. Supervisors, however, need to gain access to all programming functions. GLpH may be programmed
with a Lock code. If use of a lock code has been requested in Setup/System setup, the correct lock code
must be entered before access is allowed to the Supervisor menu.
The Lock code must be a number with 1 to 4 digits. Initial zeros will be ignored (e.g. 0123 will be read as
123).
To make it possible to use a lock code, the supervisor must enter the code number in Setup/System setup.
MAKE SURE YOU KEEP A RECORD OF THE LOCK CODE IN A SAFE PLACE, IN CASE YOU LOSE OR
FORGET IT! If you lose the lock code, please contact Sirius.
8.1.2 Setup/System setup/Serial port output to
Select from a choice of three printers or two computers, or not connected. See Section 11.
8.1.3 Setup/System setup/Autosampler tray type default
When they are installed on the autosampler, the 32 and 50 position autosampler trays are identified
automatically by the instrument via magnetic sensors. If the tray is removed for cleaning or loading, the
magnetic sensors are not active. However, the setting made here will continue to identify the tray so that it is
still recognised by the software. This option is only available on autosampler versions of GLpH.
8.1.4 Setup/System setup/Lock system on calibration failure
This option will prevent any measurements from being made if the calibration fails. Unlocking the system will
require a calibration to be done in which the failure parameters (Section 8.1.4) are not exceeded.
44
8.1.5 Setup/System setup/Lock system on calibration suspect
This option will prevent any measurements from being made if the calibration becomes suspect. Unlocking
the system will require a calibration to be done in which the suspect parameters (Section 8.1.5) are not
exceeded.
8.1.6 Setup/System setup/Use Sample IDs
Each sample must be identified before measurement. Two types of sample identification (ID) are possible:
User defined and System assigned.
The user can define a sample ID, which may be up to 13 characters including letters, spaces and numbers,
such as:
Test 001
Alternatively, GLpH can create a system-assigned sample ID, which will take the following form:
System00001
8.1.7 Setup/System setup/Prompt last sample IDs
This option is only available on autosampler versions of GLpH. If this option is selected, the instrument will
automatically suggest the last sample ID that was used.
8.1.8 Setup/System setup/Increment sample ID
This option is only available on single-sample versions of GLpH. If a sample ID ends in a numeral, GLpH can
be set up to increment that numeral automatically each time a new sample is measured, e.g.
Test 002
Test 003
System00002
System00003
8.1.9 Setup/System setup/Temp probe in sample measurements
If NO is selected, you will be asked to enter a default sample temperature. This option allows pH
measurement in small vials where there is only room to place the electrode. See Section 6.4.
8.1.10 Setup/System setup/Print sample results
Use MORE/LESS to select whether sample results are printed automatically after each measurement.
8.1.11 Setup/System setup/Allow emergency sample interrupt
This option is only available on autosampler versions of GLpH. Allows a sample run to be interrupted so that
an emergency sample can be placed in the autosampler tray. Emergency sample positions are number 29
in the 32-position tray and number 46 in the 50-position tray.
8.1.12 Setup/System setup/Do calibration after
This option can be used to set up the GLpH to calibrate automatically after a set number of consecutive
measurements. Select Disabled (0) or enter a number. In the Autosampler version, the number of
measurements is counted from the start of each tray.
45
8.1.13 Setup/System setup/Use audit trail log
GLpH will print Audit trail log forms (see example in Figure 30) to confirm that actions have been carried out.
Forms may be signed and pasted into the laboratory notebook or audit file. The use of Audit trail logs is
selected in Setup/System setup/Use Audit trail log.
Figure 30. Electrode cleaned, printout of audit trail log
8.1.14 Setup/System setup/Use user names
Press YES to enable the use of names to identify users. Selected operations and printouts will be tagged
with user’s name to assist GLP. Press NO if User Names are not required.
8.1.15 Setup/System setup/User ID PIN numbers required
If User Names have been requested, there is an option to use PIN numbers (Personal Identification
Numbers) to confirm the user’s name. The PIN must be a number with 1 to 4 digits. Initial zeros will be
ignored (e.g. 0012 will be read as 12). If the use of PIN numbers has been requested, users must set up
their own PIN numbers in Setup/Enter user names.
If a PIN number of -1 (minus 1) is entered in association with a user name, no PIN number will be requested
when that User Name is selected.
If user names are saved in GLpH at a time when use of PIN numbers was not requested, and use of PIN
numbers is subsequently requested, the previously saved User Names will all be assigned a PIN number of 1, which can be amended if required.
8.1.16 System setup/System setup/Add user during test
Press YES to enable the option of adding new user names during a test. Although this may be convenient for
some users, the ad hoc addition of new user names may infringe upon GLP rules in some laboratories.
8.1.17 Setup/System setup/Show electrode slope as
Press MORE or LESS to display electrode slope in units of percentage or mV in the calibration slope history
graph, the table of calibration history data and downloaded calibration data.
46
8.1.18 Setup/System setup/Print calibration log
Press YES to print calibration log automatically after each calibration.
8.2 Setup/Setup time and date
Press YES to display the Setup time and date dialogue box. Time and date are already setup in GLpH
before delivery to customers. To change the time and date, follow the instructions displayed.
8.3 Setup/Set calibration protocol
Press YES to display the calibration protocol dialogue box. Fifteen protocols are available. Press UP or
DOWN to select the protocol you wish to use, press YES to select, then press ESC. Press NO to delete a
calibration protocol. Calibration protocols are discussed in Section 5.4.
8.4 Setup/Install electrode, electrode parameters
Press YES to display the Install electrode, electrode parameters dialogue box (Figure 19).
8.4.1 Installing a new pH electrode
Press YES when the message Install a new electrode is highlighted. This will disable automation while a new
electrode is installed.
WARNING!
Installing a new pH electrode will cause GLpH to lose all saved pH and
calibration data relating to the old electrode. Consider whether you
want to print or download this data before installing the new electrode.
Instructions for installing a new electrode are given in Section 4.5.2. After installing a new electrode, enter
the serial number of the new electrode into the Install electrode, electrode parameters dialogue box.
8.4.2 Setting up out-of-range parameters for electrode, buffers and calibration
GLpH will display warning messages if electrode performance, buffer solutions or calibrations are out-ofrange. From the Install electrode, electrode parameters dialogue box, press DOWN to select the numbers
and percentages displayed. Enter values which correspond to your requirements. The parameters shown in
Figure 19 are sensible for most pH electrodes.
If calibration is out-of-range, a warning message will indicate that there is a problem with the pH electrode or
buffer solutions. Install fresh buffer solutions and recalibrate. If problems persist, see Section 12 for
troubleshooting suggestions.
47
8.4.3 Serial numbers for electrodes and temperature probes
Sirius pH electrodes and temperature probes for use on GLpH carry serial numbers. Whenever a new
electrode or temperature probe is installed, its serial number should be entered in Setup/Install electrodes,
electrode parameters.
8.5 Setup/Enter user names
Press YES to display the Enter user names dialogue box. This is a list of up to 20 users’ names.
To add a new name, highlight a blank line and press YES. The text entry pad and a small dialogue box will
appear. Enter the new name using a computer keyboard or the text entry pad (see Section 10.3). If the use
of PIN numbers has been requested, you will then be asked to enter a PIN number.
To delete or edit a name, highlight the name and press YES. The text entry pad and a small dialogue box
containing the selected name will appear. Press NO to delete the name character-by-character. Edit the
name using a computer keyboard or the text entry pad.
8.6 Setup/Setup actions and reminders
Press YES to display the Setup actions and reminders menu.
8.6.1 Automatic calibration, Reminders to carry out maintenance functions
Sirius recommend that all reminders are enabled when GLpH is in routine use.
The flashing message REMINDER DUE indicates that a maintenance task is due. Software insists that the
user deals with the reminder before GLpH can be used for any other task.
Actions and reminders can be programmed to occur after a fixed time period has elapsed (e.g. every 4
hours), at a fixed time of day (e.g. 8.00 am). Reminders to install fresh wash solutions or buffers can also be
set up to occur after a user-programmed number of uses. If you want an action or reminder to occur more
than once per day and also at fixed times (e.g. every six hours at 8:00, 14:00, 20:00 and 2:00), you must wait
until the first time at which you want it to occur, (e.g. 14:00) and set it up at that time.
If two or more actions or reminders are programmed to occur at exactly the same time, they will be activated
in the order of the list below. If automatic calibration comes due while reminders are due to install fresh wash
solutions and/or pH buffer solutions, GLpH will not calibrate until the solutions have been changed.
(also activated manually by pressing CAL NOW)
8.6.2 Automatic electrode calibration
Sirius recommend that automatic electrode calibration is done at least twice during the working day. Hourly
calibration is recommended for the most precise pH measurement, though at the rate of 24 calibrations per
day, it will fill the calibration history log in about 10 days. Suggestion: set automatic calibration to take place
at a time period of six hours (i.e. four times per day). Automatic calibration is also activated by pressing CAL
NOW.
GLpH begins to calibrate automatically as soon as the programmed time is reached, unless it is in active use
(e.g. measuring pH). However, it will not begin to calibrate automatically if a key has been pressed within the
last 10 seconds. If automatic calibration is aborted by pressing ESC, the deferred automatic calibration will
take place one hour after ESC was pressed.
48
8.6.3 Install fresh wash solutions
The frequency of changing wash solutions depends on the workload of GLpH. For moderate workloads with
thin (non-viscous) aqueous samples, a daily change is normally sufficient. If samples are dirty or workload is
high, wash solutions should be changed more frequently. Suggestion: if you plan to change the wash
solutions once per day, set the reminder for a fixed time every day, just before the start of the working day,
e.g. 8:00.
8.6.4 Install fresh pH7 buffer solutions
Calibration buffer solutions should be changed at least once per day during periods when GLpH is in routine
use. Fresh wash solutions should be installed before buffers are changed. Suggestion: if you plan to change
the buffer solutions once per day, set the reminder for a fixed time every day just before the start of the
working day, e.g. 8:00.
8.6.5 Refill electrode with filling solution
The pH electrode must be topped up with filling solution (normally 3M KCl solution) about once per week.
Severe measurement problems will occur if the electrode runs dry. In laboratories which work Monday to
Friday only, it’s best to refill the electrode at the end of Friday afternoon, which allows the electrode all
weekend to settle down. Suggestion: set the reminder to refill electrode with filling solution for a fixed time
once a week.
8.6.6 Order new reagents/consumables
This reminder is provided for the convenience of users, who will need to obtain new supplies of buffer
solutions and other consumables from time to time for use with GLpH. When activated, the user can prepare
a requisition form showing quantities and part numbers of items required, together with the address of their
Sirius GLpH distributor. Suggestion: set the reminder to order new reagents and consumables for a fixed
time every 30 days.
8.7 Setup/Enter special wash names
Press YES to display the special wash dialogue box. This is a list of up to 10 special wash solutions.
To add a new special wash solution name, highlight a blank line and press YES. A small dialogue box will
appear in the middle of the screen. Enter the new name using a computer keyboard or from the text entry
pad (Section 10.3).
To delete or edit a name, highlight the name and press YES. A small dialogue box containing the selected
name will appear in the middle of the screen. Press NO to delete the name character-by-character. Edit the
name using a computer keyboard or from the text entry pad.
See Section 6.5 for suggestions for special wash solution formulae.
8.8 Setup/System test options
System test options are reviewed in Section 12.5.
49
9. Audit
9.1 Overview
This section describes the audit functions of GLpH, which help users to follow codes of Good Laboratory
Practice (GLP). Other functions which help with GLP are covered elsewhere in this manual:
See Section 11 for information about LIMS output. See Section 7.3 and 7.4 for information about Method
revision numbers.
See Section 8.6 for information about Automatic calibration and Reminders to carry out maintenance
functions. The use of printed Audit trail logs to confirm actions, Serial numbers for electrode and temperature
probe, Sample identification (ID) numbers, Lock codes, User identification and PIN numbers are also
reviewed in Section 8.1.15.
9.2 Audit functions
GLpH remembers details of the last 250 calibrations and the last 850 pH measurement results. Data is
saved electronically. Rechargeable batteries preserve memory while power is off.
Saved data may be inspected by selecting Audit from the Supervisor menu. The following options are
available:
Figure 31. Audit functions available in GLpH
9.2.1 Calibration slope history graph
This summarises the results of all saved calibrations. If the calibration protocol calls for the use of two buffer
solutions, a single line will be displayed. Two lines are displayed if three buffers are used, three lines if four
buffers are used, and four lines if five buffers are used. If the calibration protocol is changed, the graph may
show a sudden discontinuity. If buffer solutions deteriorate with time (e.g. CO2 is absorbed by a pH10 buffer
solution), the slope will tend to decrease.
9.2.2 Calibration E0 graph
This graph shows the change in E0 of all saved calibrations. The term E0 is derived from the mV reading in
pH7 storage buffer solution. The expected E0 value is 0 ± 30mV. Small variations may occur due to
temperature changes throughout the day. Sudden large changes may indicate that the buffer solution has
become contaminated, or that the pH electrode is defective.
In the above graphs, the x-axis is scaled according to the number of calibrations in memory, up to a
maximum of 250. Pressing MORE advances the cursor point-by-point to the right across the graph, Pressing
UP advances the cursor by ten steps (LESS and DOWN move the cursor to the left). The results
corresponding to the points where the cursor crosses the graph are displayed beneath the graph.
50
9.2.3 Calibration history data
Lists all recent calibrations up to a total of 250. If more than 250 calibrations have been done, results of the
earliest calibrations are deleted point-by-point so that the last 250 remain listed. A typical display is shown in
Figure 32.
Figure 32. Calibration history log.
The term S1 refers to the slope between the two buffer solutions with the lowest pH values (e.g. 4 and 7).
The term S2 refers to the slope between the two buffer solutions with the next higher pH values (e.g. 7 and
10). If four or five buffers are used, the slopes S3 and S4 can be reviewed by pressing 2 and 3 on the
keypad.
The identity of the buffers is defined by the calibration protocol number. Although not shown on the screen
display, out-of-range, timeout and non-GLP warnings are also saved. See Section 11.2.9. Reminders and
warnings are displayed to indicate when the data log is becoming full.
9.2.4 pH buffer drift history
A summary of the drift in E0 as a function of time for the currently-installed pH electrode. Up to 550 days of
data can be stored. Data are obtained by reading mV once per hour when the pH electrode is in the pH7
storage solution. Every point obtained during the last month is stored. When over one month’s worth of data
has been collected, the mean E0 value and SD from all data older than one month is calculated and
displayed.
9.2.5 Sample results data
Lists all sample pH measurement results up to a total of 850. If more than 850 measurements have been
made, results of the earliest measurements are deleted point-by-point so that the last 850 remain listed. A
typical display is shown in Figure 33. Although not shown on the screen display, method revision numbers
are also saved. Reminders and warnings are displayed to indicate when the data log is becoming full.
Figure 33. Sample results log
The “flag” is a symbol which indicates that measurement was out-of-range, or that conditions during
51
measurement deviated from GLP. Meanings of flag symbols are shown in Table 5.
!
pH
out-of-range
Temperature
out-of-range
Stability
timeout
Result taken
Symbol
To erase the GLP data record, select Setup/Install electrode, Electrode parameters. Select Install electrode.
Decide whether or not to download saved data. If you then press YES to install electrode, all saved data will
be erased.
Ì
*
Ì
º
Ì
#
Ì
Ì
?
>
Ì
Ì
<
Ì
Ì
[
]
Ì
&
^
‘’
Ì
Ì
Ì
Ì
Ì
Ì
Ì
Ì
Ì
Ì
any combination not listed
above, and/or non-GLP
(see Section 9.2.6), last
calibration out of range,
next calibration out of
range.
Table 5. Flag symbols used in history logs.
9.2.6 Result record indicates deviation from GLP
GLpH calibrates electrodes and measures pH by implementing methods which have been pre-programmed
and saved. Although measurement is made automatically, users can intervene during measurement to
change the measurement conditions. If a user intervenes during measurement, the intervention is indicated
in several ways (Table 6).
Intervention
Indicated by...
Pressing TAKE RESULT before timed or stability
criterion has been satisfied
on display: ---RESULT TAKEN!--on printout: Result taken by user
in saved data: by a flag symbol
Pressing UP or DOWN to increase or decrease
stirrer speed during measurement
on printout: Non-GLP, method
changed by user!
Pressing LESS or MORE to decrease or increase
the length of timed functions (e.g. Pre-stir time)
during measurement
on printout: Non-GLP, method
changed by user!
Table 6. User intervention indicators.
52
10. Display and text entry
10.1 Display
GLpH has a 16-line, 40-column backlit liquid crystal display panel. The contrast of the display is factory-set,
but may be adjusted by using a small electrical screwdriver to turn the potentiometer to the left of the stirrer
power socket (see Figure 11).
10.2 Keypad, computer keyboard
GLpH is controlled from the 22-button keypad next to the display panel. It may also be controlled from a
computer keyboard (AT), which also allows easy entry of alphanumeric and ASCII characters. Table 7
explains the GLpH keypad and lists equivalent computer keys.
10.3 How to enter text into GLpH
You can enter, edit and delete text in GLpH for the following parameters:
User name (up to 17 characters, including spaces)
Sample ID (up to 13 characters, including spaces)
Special wash name (up to 13 characters, including spaces)
Method title (up to 27 characters, including spaces)
Electrode ID (up to 8 characters, including spaces)
ATC probe ID (up to 8 characters, including spaces)
Buffer solution ID (up to 15 characters, including spaces)
Text can be entered using an AT computer keyboard if connected to GLpH. To enter a name, type the name
on the AT computer keyboard. Press ENTER when the name is complete.
Text can also be entered using the GLpH text entry pad. The text entry pad appears automatically at any
time that text entry is requested. In the text entry pad, each letter of the alphabet is shown, together with
some accented characters, punctuation marks and mathematical signs. A small dialogue box appears above
the text entry pad. Names are entered, edited and deleted in this box.
Enter the name character-by-character from the text entry pad. Select each letter by pressing UP, DOWN,
MORE or LESS until the required character is highlighted, then press YES to enter the character. To enter a
number, press the appropriate number key on the keypad. To enter a space between words, highlight the
space between the letters E and a on the text entry pad, then press YES. When the name is complete, keep
pressing DOWN until you highlight the YES bar, which reads:
---Press YES Here When Correct---Press YES while the YES bar is highlighted.
Names are deleted by pressing NO to delete the name character-by-character from the text entry dialogue
box.
53
GLpH
Keyboard
ESC
ESC
Abort any operation which is in progress, or go back to
previous screen display, accepting any selected items
CAL
NOW
F1
Calibrate GLpH now
Emergency sample interrupt (for autosampler version only)
TAKE
RESULT
F2
Take the pH measurement result immediately, without waiting
for programmed criteria to be met. Only active during
calibration and pH measurement
PRINT
Print Screen
Prints the full contents of the screen display, if a printer is
connected.
YES
↵ enter
Yes to action any highlighted question or action which is
displayed
NO
→
Pressing No from Normal user or Supervisor menu displays
Maintenance menu.
Pressing No deletes character-by-character from certain
displays.
backspace
UP
↑
DOWN
↓
LESS
←
MORE
→
Function
UP, DOWN, MORE
and LESS are used
to move the
highlight to
different items on
the screen display
LESS and MORE
may be used to
decrease or
increase numerical
values which are
highlighted, e.g.
when editing a
method
Increase stirrer speed during a pH
measurement
Decrease stirrer
measurement
during
a
Decrease the length of certain timed
functions (shown by square-bracketed
numerals e.g.[60] in the bottom right
hand corner of the display)
Increase the length of certain timed
functions (denoted by square-bracketed
numerals e.g.[60] in the bottom right
hand corner of the display)
Table 7. Key functions.
54
speed
11. Output from GLpH
11.1 Output to printers
11.1.1 Types of printout
If a printer is properly connected to GLpH and specified in System Setup, various types of printout can be
made (see Table 8). Information is sent from GLpH as graphics (letters and numbers, lines, boxes, and
reverse video), or as text (letters and numbers only, in ASCII format).
Type of printout
description
Graphics (may not be printed correctly except on fully supported printers)
Any screen display
Printed on request by pressing PRINT button
Audit trail logs
If Setup/System setup/Use Audit trail log has been
selected, Audit trail logs are printed automatically after the
actions below have been completed by the user.
1. Install fresh water wash solutions
2. Install fresh pH buffer solutions
3. Refill electrode with filling solution
4. Special electrode clean
5. Confirmation of method creation or editing
Text
pH results
Printed automatically after each measurement (if
programmed), and at fixed times if method specifies pH print
interval during monitoring of sample pH.
Calibration results
Printed automatically after each calibration if Setup/System
setup/Print calibration log has been selected
LIMS output
All saved data from the files below may be printed on
request if Audit/Download data to PC or LIMS has been
selected
1. Calibration history data: results of up to 250 electrode
calibrations
2. Sample results data: results of up to 850 pH
measurements
3. Hourly pH7 mV (E0) data: hourly electrode reading in pH7
buffer
Requisition
Order requisition for reagents/consumables
Table 8. Types of printout from GLpH
11.1.2 Printers fully supported by GLpH
The following three printers have been tested and verified for correct performance, and are fully supported
by GLpH.
Citizen iDP3540-F40RF230-GB (Made in Japan)
55
iDP3540 is a 40-column plain-paper printer. It prints text at the rate of 2.4 lines per second. The letter G in
the part number indicates that it has graphics printing capability, which is a necessary requirement.
Citizen 3550S (Dot matrix) or Citizen CBM 1100 (Thermal)
DH Technology DH4710 (Made in USA)
DH4710 is a 40-column plain-paper printer. It prints text at the rate of 4 lines per second.
Epson TM-300A (Made in Japan)
TM300 is a 40-column plain paper printer. It prints text at a rate of 3.5 lines per second.
11.1.3 Setting up GLpH for communication with printer
Choose one of the following options to set up GLpH with a supported printer:
From Supervisor menu, Setup/System setup/Serial port output to, select the appropriate printer
Printer iDP3540
Printer DH4710
Printer TM300
11.1.4 Other printers
GLpH may be used with other 40-column serial printers. While normal text characters will probably be
printed correctly, graphical lines, reverse video displays and large-format numbers may be printed
incorrectly. GLpH may not be used with printers with a parallel interface. Select the computer ASCII or
computer OEM option to set up GLpH with a non-supported printer. In this mode GLpH will output data in
ASCII or OEM character set format. Refer to the manual supplied with the printer for instructions.
11.1.5 Setting up a printer for communication with GLpH
The printer must be set up before use for correct communication with GLpH. The following settings must be
made in the printer. Refer to the manual supplied with the printer for instructions.
Printer settings: Baud rate 2400
8 Data bits
1 Stop bit
no parity
11.1.6 Cables to connect GLpH to printers
GLpH to Citizen iDP3540
9-way D socket to 25-way D plug (Sirius part number 040310)
GLpH to DH4710
GLpH to TM300
9-way D socket to RJ45 female telephone jack (Sirius part number 040311)
9-way D socket to 25-way D plug (Sirius part number 040310)
Sirius cannot supply cables to connect GLpH to non-supported printers. However, cables can be made up
using the serial port pinout information in Table 9 for the GLpH serial output.
56
Pin
Connection
1
not connected
2
RXD (receive data)
3
TXD (transmit data)
4
not connected
5
GND (ground)
6
not connected
7
not connected
8
not connected
9
not connected
Table 9. Serial port pinout information
11.1.7 Connecting the printer
Connect the cable between the printer and the 9-pin D connector on GLpH (Figure 11). Switch on the printer
and place it on-line.
NOTE: To print correctly, Citizen iDP3540 printer must be on-line. If it is not on-line when a print command is
sent, it may still print, but the printout may be unintelligible.
11.2 Using GLpH with computers
11.2.1 Types of data output from GLpH
All types of data listed in Table 8 (page 55) can be sent from GLpH to a computer (PC). However, the PC
must be running suitable software to be able to receive and process the data. The process of sending data to
the PC is called ‘downloading’.
11.2.2 Setting up a PC for communication with GLpH
The PC must have a serial port available (usually called COM1 or COM2), and software to allow it to receive
data through that serial port. The following communications settings must be selected:
Bits per second
Data bits
Parity
Stop bits
Flow control
2400
8
none
1
none
11.2.3 Cables to connect GLpH to PC
Sirius supply a cable for connection between the 9-way D-socket on GLpH and a 25-way D-socket, which fits
COM2 ports on many desk-top computers. The part number of this cable is 0403008. A 9-way D-socket to
57
9-way D-socket, which fits COM1 ports on many laptop computers, is also available. The part number of this
cable is 0403009. These cables may not fit all PCs.
11.2.4 Setting up GLpH for communication with a PC
From supervisor menu, select Setup/System Setup/Serial port output to. Choose the Computer ASCII
option.
11.2.5 Using HyperTerminal to capture text data downloaded from GLpH
HyperTerminal is a program in Microsoft® Windows. HyperTerminal will enable normal text characters
(ASCII or OEM character sets) to be downloaded correctly. In computer mode GLpH only sends the text part
of any screen.
Use the appropriate cable to connect between the printer output of GLpH and the computer. Note which
COM port on the computer that the cable is connected to.
On the PC, select Programs/Accessories/Communications/HyperTerminal. Follow the instructions in Figure
34.
58
Figure 34. Setting up communications in HyperTerminal
59
11.2.6 Downloading data from GLpH to a PC running HyperTerminal
With the PC set up and ready to receive data, go to GLpH. Select Audit/Download data to PC or LIMS.
Select which data you wish to download. Follow the instructions displayed on GLpH. Data will appear on the
computer screen as it is downloaded.
After 100% of the data has been downloaded, GLpH will ask Clear history Y/N? Press YES or NO to close
the download from GLpH. Then go to HyperTerminal in the PC, select Transfer/Capture text/Stop. You can
now close HyperTerminal. The downloaded data will be in the PC. The file may now be opened in a
spreadsheet or word processor to allow manipulation of data and creation of graphs.
11.2.7 Example of downloaded calibration data
The example below shows one header line plus ten lines of downloaded calibration data, after it has been
parsed in a spreadsheet. GLpH was running calibration Protocol no. 3.
1
2
40
41
42
43
44
45
46
47
48
49
10-Mar-1998
10-Mar-1998
10-Mar-1998
10-Mar-1998
10-Mar-1998
10-Mar-1998
10-Mar-1998
10-Mar-1998
10-Mar-1998
10-Mar-1998
3
09:29
09:59
10:29
10:59
11:29
11:59
12:29
12:59
13:29
13:59
4
5
6
7
23.51
24.68
24.56
26.20
26.70
27.10
27.40
27.54
27.65
27.77
23.50
24.66
25.54
26.13
26.61
26.98
27.29
27.40
27.45
27.56
22.99
23.98
24.74
25.34
25.84
26.26
26.59
26.78
26.94
27.10
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
8
9
0.00 -10.48
0.00 -10.31
0.00 -9.75
0.00 -9.52
0.00 -9.32
0.00 -9.02
0.00 -8.77
0.00 -8.52
0.00 -8.42
0.00 -8.36
10
11
12
13
14
98.22
98.21
98.22
98.20
98.19
98.18
98.19
98.19
98.15
98.15
94.22
94.11
94.02
94.01
93.99
93.99
93.97
94.00
94.03
94.04
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
00000003
00000003
00000003
00000003
00001003
00000003
00000003
00000003
00000003
00000003
Key to columns 1 to 14
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Calibration number (up to 250 consecutive numbers; if more than 250 calibrations have been
done, the earliest lines of data will have been overwritten)
Date
Time
Temperature of 1st buffer solution
Temperature of 2nd buffer solution
Temperature of 3rd buffer solution
Temperature of 4th buffer solution
Temperature of 5th buffer solution
mV in pH7 buffer solution
Slope S1, buffer1-buffer2
Code indicating state/condition of GLpH during calibration; as follows:
60
Interpreting the code
The code number in the last column is an eight-digit number written in hexadecimal* format, which indicates
the state of GLpH at the time that the calibration was done. It is calculated by taking the sum of all the
numbers from Table 10 which represent states and conditions which were active at the time the calibration
was done. In the examples above, code 00000003 means that calibration protocol no.3 was in effect, while
code 00001003 means that calibration protocol no.3 was in effect, and also that the pH10 result timed out,
that is, it did not reach the required stability criterion.
State/condition
Number
State/condition
Number
Calibration protocol 1 in use
00000001
New buffers installed since
previous calibration
00000010
00000002
Stability timeout in buffer 1
00000020
00000003
00000040
00000004
00000080
00000005
00000100
00000006
00000200
00000007
pH result taken in buffer 1
using TAKE RESULT button
00000400
00000008
00000800
00000009
00001000
0000000a
00002000
0000000b
00004000
0000000c
pH electrode refilled since
00008000
0000000d
Special electrode clean done
since previous calibration
00010000
0000000e
Wash solutions changed since
00020000
0000000f
New electrode installed since
00040000
Table 10. Downloaded calibration data codes
*Hexadecimal is a numerical scale written to the base 16. 1 – 9 are the same in decimal and hexadecimal.
Decimal 10 – 15 are represented by a – f in hexadecimal.
61
11.2.8 Example of downloaded sample results data
1
2
3
4
5
6
7
8
9
11
12
14
15
16
19
20
21
22
1
1
1
1
7
6
7
7
7
1
1
1
1
7
4
8
8
8
01
10
00
08
0a
11
1d
1e
0d
6.943
6.940
6.943
6.884
6.955
6.941
6.946
6.945
6.946
23.61
23.44
23.20
23.20
19.56
22.53
22.79
22.74
22.78
3
3
3
3
4
4
1
1
1
10-Mar-98
10-Mar-98
10-Mar-98
10-Mar-98
11-Mar-98
11-Mar-98
11-Mar-98
11-Mar-98
11-Mar-98
15:48
15:49
15:57
15:59
10:45
14:52
14:55
14:56
14:59
1
2
3
4
5
6
7
8
9
Sample ID number
Method number
Method revision number
Code indicating problems with measurement: see below
pH of sample
Temperature of sample
User number from 1 to 20; cross-references with user name
-1 means User ID option not selected in Setup System
-2 means unidentified user
Date
Time
11.2.9 Interpreting the code
The code number in column 4 is a two-digit number written in hexadecimal format, which indicates problems
with the pH measurement. It is calculated by taking the sum of all the numbers from Table 11 which
represent problems which occurred when the measurement was done. In the examples above, code 00
means there were no problems. Code 08 means that the pH result was out-of-range. Code 11 means that
the result was taken using the TAKE RESULT button, and also that the user intervened while the electrode
was in the sample, for example by changing the stirrer speed using the UP/DOWN buttons or changing a
timed operation using the MORE/LESS buttons.
62
Problem
Number
pH result taken (using TAKE RESULT) button
01
pH result taken after stability timeout
02
Temperature of sample out-of-range
04
pH of sample out-of-range
08
User intervened during measurement (i.e. non-GLP)
10
The current calibration is out of range
20
The next calibration is out of range
40
Table 11. Downloaded sample data codes
11.2.10 Example of downloaded hourly pH7 mV (E0) data
1
2
3
4
5
6
7
8
9
10
11
12
+9.038
+9.311
+9.968
+9.194
+9.029
+9.970
+9.828
+9.937
+9.173
GLpH serial number 951201
Electrode Kel-0101 installed 15-12-1995
15-12
16-12
N
N
4
9
+9.602
+9.807
+9.245
+9.488
1
2
3
4-12
Date (day and month)
N = normal data. C= compacted data (see below)
Number of values stored for that day (maximum 24 if GLpH switched on all the time)
Hourly reading of mV in pH7 storage buffer solution
Data for the last 30 days are displayed in the form above. If more than 30 days of data are stored, the
earliest data are compacted. Compacted data show the mean and standard deviation (SD) of each day’s
data, up to a maximum of 520 days. Thus, a total of 550 days of hourly mV data can be saved.
63
12. Troubleshooting
12.1 Electrode troubleshooting
The most common type of problem with GLpH is that the pH electrode or buffer solutions are out of range.
This will be indicated by a message which appears on the screen, either after a suspect calibration, or after a
suspect hourly mV check. Use the Table 12 to diagnose possible problems.
Problem
Possible action to take
pH electrode is physically broken.
Replace electrode.
pH electrode is dirty.
Use special electrode clean.
pH electrode not properly plugged into
GLpH.
Plug it in!
Temperature probe is faulty.
Check performance in System test options.
Program set temperature in Autosampler version
One or more buffer solutions is
contaminated.
Change buffers and repeat calibration.
Water wash 2 is contaminated.
pH value of wash water displayed on screen
during wash should be pH7 ± 2. Change water if
necessary.
Out-of-range parameters have been
incorrectly set, or are too strict.
Re-set parameters in Setup/Install electrode,
electrode parameters.
Not enough buffer or sample in vial or
beaker; electrode junction not properly
immersed in solution.
Use more solution in vial or beaker; lower
electrode further in sample.
Isopotential point of electrode is
incorrectly entered.
Check isopotential point in Setup/Install
electrode, electrode parameters. Try entering
a default value of pH7, 0mV.
Table 12. Electrode troubleshooting
12.2 Maintenance menu
Two Maintenance menus are available in GLpH.
The Normal User maintenance Menu is displayed from the Normal User Menu by pressing NO. It allows the
user on demand to change wash solutions, change calibration buffers and refill the electrode with filling
solution. Audit trail logs are printed if their use has been enabled in Setup.
The Supervisor maintenance menu is displayed from the Supervisor menu by pressing NO. It allows the
supervisor on demand to carry out all the options shown in the menu displayed in Figure 35.
Selecting Disable automation then pressing YES will disable all automated functions until another key is
pressed.
Selecting Special electrode clean then pressing YES will enable a special electrode clean to be done. See
Section 6.5 (audit trail log printed if enabled in Setup).
Selecting Change wash solutions then pressing YES will enable the user to change wash solutions on
demand (audit trail log printed if enabled in Setup).
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Selecting Change calibration buffers then pressing YES will enable the user to change calibration buffers on
Selecting Refill electrode with filling solution then pressing YES will enable the user to refill the electrode on
Selecting Print reagents/consumables requisition then pressing YES will display a “requisition form”. The
user can enter quantities required of various consumables and other items which might be required for use
with GLpH, and print a requisition form which lists these items and the address of their authorised Sirius
distributor.
Figure 35. Maintenance menu
12.3 Lubrication
The mechanical slides in GLpH must be lubricated from time to time. A good quality No. 2 lithium soap
grease should be used (Sirius part no. 0705007). This lubrication would normally be done by a service
engineer during an annual routine maintenance programme.
65
12.4 Electromechanical problems
GLpH detects problems in the motion of the electrode holder or tower. As soon as a problem is detected, all
motion is disabled. The instrument beeps once per second, and an error message is displayed. The problem
must be investigated and solved before use of the instrument can be resumed. If the error message
continues to be displayed, it is still possible to access the System Test Options. While GLpH is beeping, type
01234 at the rate of one character per beep. The System test options menu will be displayed. The fault must
be fixed and the instrument reset by turning off and on before normal operation can be resumed.
Error message
Caused by...
Things to check...
ERROR 3: home
position not found
The side-to-side motion of
the tower was jammed and
it could not move to its
‘reference position’ on the
far left.
Tower hit some external object?
Tower or tower base plate
rubbing on some fixed part of
GLpH? (See Section 4.4.1, items
7 and 8.)
Opto sensor on the underside of
the tower base plate failed? (To
check, see Section 12.5.2.)
ERROR 4: Z motor
driving up
The upwards motion of the
electrode holder was
jammed and it could not
move to its ‘reference
position’ at the top of the
tower.
Electrode holder hit some
external object?
Cables tangled?
Arm is jammed?
Failed opto sensor at top of
tower? (To check, see Section
12.5.2.)
ERROR 7:
Autosampler forwards
The autosampler tray tried
to move but failed to find
the right position.
Sample vials correctly seated?
Tray jamming against something?
Autosampler cable connected to
the instrument?
ERROR 7:
Autosampler
backwards
The autosampler tray tried
to move but failed to find
the right position.
Sample vials correctly seated?
Tray jamming against something?
Autosampler cable connected to
the instrument?
ERROR 13: X motion
failure
ERROR 14: lost X
position
The tower moved from
side-to-side but was not
able to locate the correct
beaker or vial position.
The tower tried to move to
a certain beaker or vial
position but found a
different position.
Tower hit some external object?
Tower or tower base plate
rubbing on some fixed part of
GLpH (see Section 3.4.1, items 7
and 8)?
Cables tangled?
Opto sensor on the underside of
the tower base plate failed? (To
check, see Section 12.5.2.)
Table 13. Error messages
66
12.5 Selftest options
Select Setup/System test options to request selftest options in which GLpH automatically checks
mechanical and electronic components to verify normal operation. These selftest options are shown in
Figure 36, and are useful for investigating service problems. All normal automation (e.g. automatic
calibration) is disabled while System test options are in use.
Figure 36. GLpH selftest options
12.5.1 Test and set clock chip
Function: to check/amend the date and time saved in GLpH. This display is identical to that displayed after
selecting Setup/Set up time and date.
12.5.2 Test hardware
Select Test hardware options are shown in Figures 37 and 38.
Figure 37. Test hardware options for single sample GLpH
Figure 38. Test hardware options for GLpH with autosampler
67
Testing positions and movements
Select XZ Arm, then select a buffer, wash or sample position, then press YES.
Then select Move to lift the probes from their current position and place them in the requested position.
Alternatively, select Move with user Z control to lift the probes and place them above the requested
position without lowering (useful for testing alignment)
Additional options are offered if a position in the autosampler tray has been selected.
The two lines at the bottom of the screen indicate which Opto sensors are open or closed.
Calibrate mV circuitry
Select ATOD1 to calibrate the mV circuitry. You will need a calibrated mV source to carry out this option.
To re-set a point on the mV scale, first disconnect the pH electrode. Connect a calibrated mV source which
is set up to provide a signal of at least ±300mV. Check the mV display to make sure it shows a value close to
the input from the mV source. Press YES. From the keypad, enter the setup lock code 9 2 1, then press
YES. The message mV should now be... will be displayed. Enter the exact value of the input mV from the
mV source, then press YES. The new mV value should be displayed.
This function is used to make small adjustments to the linearity of the A-D converter. DO NOT USE THIS
FUNCTION TO ATTEMPT TO RE-SET ZERO mV. Checking and resetting zero mV requires adjustment on
the printed circuit board, and should only be attempted by a service engineer.
Calibrate temperature circuitry
Select ATOD2 to calibrate the temperature circuitry.
To re-set a point on the temperature scale, place the temperature probe into a beaker containing water,
alongside an accurate thermometer. Press YES, and select Calibrate temperature circuitry. From the
keypad, enter the setup lock code 1 2 9, then press YES. The message temperature should now be... will
be displayed. Enter the exact value of the temperature shown on the thermometer, then press YES. The new
temperature value should be displayed.
The temperature probe used on GLpH contains a Pt100 platinum resistance thermometer. This function is
used to compensate for small deviations between the performance of individual probes.
Test stirrer
Select Stirrer to test the stirrer at normal speed (50%), high speed (75%) and hyper speed (100%). Pressing
MORE or LESS will increase or decrease the speed in 1% increments.
Buzzer
Select Buzzer to test the buzzer.
12.5.3. Keyboard and keypad
Select Keyboard and keypad to test for correct output from keypad on GLpH. Each key pressed will be
identified on the screen display. This function also identifies keys pressed on a computer keyboard, following
the rules explained in Table 7 (page 54).
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13. Parts and accessories
13.1 Ordering parts
The following parts and accessories may be ordered via your Sirius distributor. Descriptions are for guidance
only and may be changed without notice.
Part No.
Description
1201001
1201002
1203001
1220006
GLpH single sampler
GLpH autosampler (without sample tray)
Autosampler for GLpH without tray
Printer for GLpH
Software and upgrades
0905010
0905011
0905012
Software upgrade for GLpH (v.2 hardware) to Rev 2.014, French
Software upgrade for GLpH (v.2 hardware) to Rev 2.014, English
Software upgrade for GLpH (v.2 hardware) to Rev 2.014, German
Electrodes for GLpH and accessories
0485002
0485005
0485007
0485009
0485011
1402015
1804002
1402012
1804001
pH Electrode, Ag/AgCl general purpose CAL+filling solution, fits GLpH
pH Electrode, Ag/AgCl sleeve junction CAL+filling solution, fits GLpH
pH Electrode, Ag/AgCl 4.3mm diameter CAL+filling solution, fits GLpH
pH Electrode, Ag/AgCl flat ended CAL+filling solution, fits GLpH
pH Electrode, Ag/AgCl green glass CAL for high pH+filling solution, fits GLpH
Gel filling solution for Sirius electrodes 2x60ml bottles
Electrode 3 point calibration service
Filling solution, 3M KCl, 2 X 60ml, for Ag/AgCl electrode
Sirius Four-Plus pH electrode standardization service, per electrode
Autosampler and trays
0304001
0304003
0304005
0304007
0802001
1001001
0105040
1004001
32 position sample tray
50 position sample tray
Temperature controllable 32 position sample tray
Temperature controllable 50 position sample tray
Conversion kit for GLpH (v.1 hardware to v.2 hardware)
Service drawer module
Autosampler positioning tray
Autosampler cover
69
Part No.
Description
Manuals
0910001
0912001
Instruction manual for GLpH, March 1998 edition
Service manual GLpH
Vials, beakers and accessories
0304022
0304012
0305011
0304010
0304011
Glass temperature control vessel, holds sample vial
Calibration vials for GLpH, pack of 6
Wash beakers for GLp-series instruments, pack of 3
pack of 12 polyethylene vials, for 32-position tray
Vial, glass, 75x24mm, Box 100
Buffer Solutions
1402001
1402002
1402003
pH 4.01Buffer Solution 475ml
pH 7.0 Buffer Solution 475ml
pH 10.01 Buffer Solution 475ml
Spare parts/general accessories
0405011
0408021
0607001
0607004
0210002
0210005
0215002
0403008
0403010
0403011
0403009
0705007
0402032
0215003
0215006
0301029
0402041
0410001
0410002
Main control board
Temperature probe, fits GLp-series instruments
Stirrer including paddle, fits GLpH
Paddle, fits stirrer 0607001
GLpH vial plate v2
GLpH electrode block
GLpH front cover
Cable GLp-series instruments.-PC (9w D socket to 25w D-socket)
Cable GLpH-Printer iDP3540/TM300
Cable GLpH-Printer DH4710
Cable GLp-series instruments.-PC (9w D socket to 9w D-socket)
Lubricating grease for X-Y-Z motion slides, 60ml bottle
pH shorting plug
Sample Beaker Station - GLpH
Sample tray dust cover
Tubing connectors for water, set of 2
Black cable sleeving
Keyboard plastic cover
Small Keyboard
Packaging
1101001
1101002
GLpH unit packaging
Autosampler unit packaging
Prices for service spares and other parts will be quoted on request.
70
14. Using Auto-Run
14.1 Overview
Auto Run is a feature of GLpH v2.014, Hardware 2. It is intended for use on single-sample
instruments only.
When running a method which includes Auto Run, GLpH will start by measuring pH of a sample as normal.
After measuring pH it will wash the probes in the wash solutions, then it will move the probes back to the
sample position and lower them into the sample, and make another measurement. GLpH will then continue
to measure and wash, measure and wash in a continuous cycle, with no need for the user to press any
button. GLpH will terminate the Auto Run session only after the ESC button is pressed.
14.2 Instructions
First, make the following selections in Setup/System setup/Use sample IDs?
Use sample IDs?
select System assigned. This allows GLpH to
create a new sample ID number (up to 10,000
numbers) at the start of each pH measurement.
Thus GLpH will not wait before measurement for
the user to enter the sample ID.
System lock code
disabled
Lock system on calibration failure?
NO
Lock system on calibration
suspect?
NO
Increment sample IDs?
YES. This will allow GLpH to increment the
sample ID number by 1 before each time the
probes lower into the sample.
Do calibration after
10 samples. Automatic calibration will be done,
then Auto Run will continue.
Next, while creating or editing a method, select YES to the question Auto run next sample. If Auto Run next
sample has been selected, then also select timed readings (240 seconds). This allows for about 12 pH
measurements per hour.
Note that if GLpH is in Auto Run mode, the memory will be quickly filled with sample results and calibration
data. To clear the memory, go to Install electrode, electrode parameters. Ask to Install a new electrode.
GLpH will offer to erase all data from the memory. Alternatively, new electrode. GLpH will offer to erase all
data from the memory. Alternatively, download the data to a computer (GLpH will offer the option to erase
memory).
71