P r o d u c t i v i... Enhance Productivity by Reprocessing Raw Data with DoScan

application
GC/MS
P ro d u c t i v i t y To o l s : D o S c a n
Enhance Productivity by Reprocessing Raw Data with DoScan
Introduction
What is DoScan?
A modern analytical laboratory handles an
immense quantity of sample information. In
order for the laboratory to be efficient, that
information must flow from sample preparation
through data acquisition and reduction and
ultimately into reporting and into the company’s
electronic ocean. Any individual area in the
process can become a bottleneck inhibiting the
efficient flow of information and causing a
decrease in productivity. In medium to high
sample volume GC/MS analyses, situations
frequently occur in which the analyst is
required to reprocess a complete or partial
sequence or batch of samples. Fortunately,
there are numerous productivity-enhancing
tools contained within Agilent Technologies'
MSD Productivity ChemStation software. These
tools, which help the operator to optimize the
flow and to reprocess information, include:
DoList, Qedit, and DoScan.
DoScan is one of the MSD Productivity
ChemStation tools designed to increase
laboratory productivity. It is an interactive
reprocessing utility that facilitates the flow
of information for the analyst. DoScan differs
from the other ChemStation productivity tools
in that it allows the analyst to select various
mass spectral scans or chromatographic peaks
for searching in a commercial mass-spectral
library database or in a user-created library.
The DoScan function is available in both the
Enhanced and Environmental data analysis
modes of the MSD Productivity ChemStation
software.
DoList is a tool for reprocessing a single sample
data file or a batch of data files in a manner
similar to that used in the original processing
(publication no. 5968-4366E). Qedit, which
is a quantitation-results editor, allows the user
to visually review and correct integration and
retention-time identification of compounds and
recalculate results and update the existing
quantitation database (calibration data).
DoScan is especially useful when a number of
unknown peaks are found in a chromatogram
that has been acquired in a scan mode of
operation. Rather than selecting the peaks
one-by-one and library-searching and printing
the results individually, DoScan allows the
analyst to select at once all the peaks that
require further identification and to then print
a library report showing the best matches
for all the selected peaks. As a result, in long
chromatographic runs in which there are many
unidentified peaks, DoScan can produce significant savings in analyst time.
Productivity Tools: DoScan
How Does DoScan Work?
DoScan is a data-reduction function
found under Tools in the Data
Analysis menu as illustrated in
Figure 1. Once DoScan is activated,
a Report dialogue box appears. See
Figure 2. In the Enhanced version
of the ChemStation, the user can
select one of two choices. The first
choice in the Select a Report Option
dialog box allows the analyst to
generate a ChemStation Library
Search Report that shows the
unknown scan compared with the
library spectrum. In addition, the
five major mass spectral ions are
extracted, information that is useful
in determining the purity of the
unknown peak. At the bottom of the
page, the three best matches from
each library are shown along with
the corresponding quality value.
This Library Search Report provides
the information necessary to
identify an unknown. The second
choice in this dialog box allows the
analyst to select a user-generated
macro for the library searching and
report style.
In the Environmental Data Analysis
mode, an additional report style,
Report LSC, is available. See
Figure 3. The LSC (Library Search
Compound) provides a report of
non-target compounds or of tentatively identified compounds.
Figure 3. The Select a Report
Option dialog box from the
Environmental Data Analysis
mode; this mode of operation
provides the Library Search
Compound report style.
Figure 1. Activating the DoScan Productivity Tools in Data Analysis under
the Tools menu item (in the Enhanced version of ChemStation).
Figure 2. The Select a Report
Option dialog box in the Enhanced
Data Analysis mode; two report
options are available.
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Productivity Tools: DoScan
Selecting Peaks for the
Library Search
After the Select a Report Option
dialog box is closed, the mouse
cursor is activated in the Annotation
mode. Clicking both mouse buttons
simultaneously selects a given peak
in this mode. When both mouse
buttons are clicked, the scan closest
to that mouse pointer in the total
ion chromatogram (TIC) is selected
for the library search and the peak
of interest is designated with a small
plus sign (+). The zoom functions
of the MSD Productivity ChemStation software that utilize the left
and right mouse buttons are active
during this operation. Hence the
analyst can select points on the
up-slope and down-slope of the
peak to determine sample purity
and to verify the match quality of
the searched spectra. Once all the
peaks have been selected, the
DoScan list is activated. A report
is generated by clicking on the
Tools menu item entitled Process
Scan List as illustrated in Figure 4.
See Figure 5 on the following page.
Figure 4. After selecting all the peaks for the library search, the DoScan
list is activated by Process Scan List under the Tools menu item.
DoScan is only one of the many
productivity tools provided with the
MSD Productivity ChemStation
software that allow the laboratory
analyst to be more efficient. When
utilized effectively, DoScan can
save considerable time and lead to
increased productivity.
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Productivity Tools: DoScan
Figure 5. An example of a
Library Search Report for one
compound; the report includes
actual spectrum (top), best
three library hits from two
different libraries (bottom),
and the five select-ion chromatograms for the five largest
abundance’s (right).
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Information, descriptions and
specifications in this publication
are subject to change without notice.
Copyright © 1999
Agilent Technologies Company
All rights reserved. Reproduction
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Printed in the U.S.A. December 1999
(23) 5968-4365E