: Modification of AOAC Official Method 998.12 to... Study of Proposed Method Modification to AOAC 998.12 Filtration and/or Centrifugation

: Modification of AOAC Official Method 998.12 to... Study of Proposed Method Modification to AOAC 998.12 Filtration and/or Centrifugation

Study of Proposed Method Modification to AOAC 998.12
1. Study Title: Modification of AOAC Official Method 998.12 to add
Filtration and/or Centrifugation
2. Study Directors / Participating Laboratories
1.
Co-Study Director
Dana Krueger
Krueger Food Laboratories, Inc.
45 Manning Road
Billerica MA 01821
Phone: 978-667-6900
Fax: 978-667-6999
[email protected]
2.
Co-Study Director
Dr Karyne Rogers
National Isotope Centre
GNS Science
PO Box 31-312
Lower Hutt, New Zealand
Phone: +64 4 570 4636
Fax: +64 4 570 4657
[email protected]
3.
Co-Study Director
Klaus Beckmann
Quality Services International GmbH
Flughafendamm 9a
28199 Bremen, Germany
Phone: +49 - (0)421 - 59 47 70
Fax: +49 - (0)421 - 59 47 71
E-Mail: [email protected]
4.
Test Material and Study Coordinator
Jo Marie Cook
Florida Department of Agriculture and Consumer Services
3125 Conner Blvd,, Bldg #3
Tallahassee, FL, 32399-1650 USA
Phone: 850-617-7505
Fax: 850-922-9110
[email protected]
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Study Description
1. Principle: Method 998.12 determines the presence of C-4 (corn or cane sugars) in
honey by comparing the carbon isotopic value of whole honey with its internal
protein. The method may falsely indicate the presence of C-4 sugars in certain
honeys such as New Zealand Manuka honey due to high pollen content which is
extracted with the protein. Centrifugation and/or filtration are proposed as
modifications to the method to assure accurate determination of C-4 sugars.
2. Scope and Applicability: This method is applicable to the measurement of C-4
(corn and cane) sugars in honey at a concentration >7%
3. Test Materials/matrices: Four pure honeys and one adulterated honey:
U.S. honey which has passed the 998.12 C-4 test
German honey which have passed the 998.12 C-4 test
two New Zealand Manuka varieties which have failed the 998.12 C-4 test
one U.S. honey adulterated with 15% corn syrup.
4. Test sample preparation and handling: Honeys will be provided by laboratories 1,
2 and 3. Identical test tubes will be provided to each of the contributing laboratories.
The laboratories will fill each of 65 tubes with 30 – 35 gm of honey; seal with cap
and teflon tape and ship to laboratory 4. Providing laboratories will assure
homogeneity by conducting homogeneity studies before shipping their samples.
Laboratory 4 will label and randomly number the test samples and ship them to all the
collaborating laboratories. Samples will be shipped in insulated containers by
expedited air transport to collaborator locations so as to arrive during the standard
work week. The collaborating laboratories will pay for test material shipment.
5. Collaborative Study Design: The study will be conducted on five matrices as blind
duplicates. Three sets of separately blinded duplicates will be provided, one for
analysis by 998.12 as written (10 test samples), one for analysis with the addition of
filtration (10 test samples) and one with the addition of centrifugation and filtration
(10 test samples) for a total of 30 test samples. Random identification numbers will
be assigned to each of the blind duplicate materials. Laboratories will be asked to
analyze the samples as described in 998.12 with only the modifications described in
Appendix A. Only laboratories experienced in analysis using 998.12 will participate
so no practice samples are necessary.
Method: See Appendix A for description of the method modifications to be
followed. A copy of 998.12 is also attached.
Collaborators: See Appendix B for listing of Collaborators.
Reporting Raw Data: Four data points are to be reported for each material:
1. Average δ13C value (‰) Whole Honey
2. Average δ13C value (‰) Protein Extract
3. Difference (Honey – Protein Extract) (‰)
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4. %C4 Sugars
Collaborators will be asked to supply any modification made to 998.12 other than
those specified in Appendix A. Excel data reporting sheets will be emailed to the
collaborators. (see Appendix C). All results will be sent to laboratory 4 who will
provide the key to the randomized test materials and submit the results to the co-study
directors, laboratories 1,2 and 3. The study directors will evaluate the data,
generate tables from the raw data received and prepare the Study Report.
Analyzing the Raw Data: Descriptions of the blind duplicate matrices will be
included with the tables of raw data. Determinations will be made of standard
deviations for repeatability (Sr) and reproducibility (SR), relative standard deviations
for repeatability (RSDr) and reproducibility (RSDR), number of statistical outlier
laboratories, and HORRAT value (RSDR/predicted RSDR) if applicable. Cochran and
Grubbs tests will be used to determine outliers.
Miscellani: Additional appendices contain a letter with instructions to participants
(Appendix D), and a study materials receipt form (Appendix E).
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Appendix A:
Test 1. Unfiltered:
Perform method 998.12, using protein preparation method 998.12 C (1)
Test 2. Filtered:
Perform method 998.12, except substitute for the protein preparation method 998.12 C
(1) the following:
Dilute honey in water (1:1), warm to 50C and vacuum filter the solution through a paper
filter with a mesh size of <10 µm (Macherey & Nagel, MN 617 or equivalent). Continue
with protein preparation method 998.12 C (1) starting from “Add 2.0 mL NaWO4
solution…”
Test 3. Centrifuged and Filtered:
Perform method 998.12, except substitute for the protein preparation method 998.12 C
(1) the following:
Add 5-10 mL H2O to 10-12 g honey in a 50 mL centrifuge tube. Mix well, heating if
necessary to aid dissolution. Centrifuge the sample at 3000 rpm for 5 min to remove fine
material such as dust and pollen. Warm the sample to 50C and carefully decant the
supernatant to a vacuum filter with glass filter with a mesh size of <10 µm (Whatman
GF/C or equivalent) to remove any floating insoluble particulate material such as pollen
that was not removed by centrifuging. Continue with protein preparation method 998.12
C (1) starting from “Add 2.0 mL NaWO4 solution…”
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Appendix B: List of Collaborating Labs
1.
Dana Krueger
Krueger Food Laboratories, Inc.
21 Alpha Road
Chelmsford, MA 01824
Phone: 978-256-1220
Fax: 978-256-1222
[email protected]
2.
Dr. Andy Phillips or Nicola Lang
National Isotope Centre
GNS Science
30 Gracefield Road
Graceville, Lower Hutt, 5010
New Zealand
Phone: +64 4 570 4878
Fax: +64 4 570 4657
[email protected]
3.
Klaus Beckmann
Quality Services International GmbH
Flughafendamm 9a
28199 Bremen, Germany
Phone: +49 - (0)421 - 59 47 70
Fax: +49 - (0)421 - 59 47 71
[email protected]
4.
Jonathan S. Haché, Chemist
Ottawa Laboratory (Carling) | Canadian Food Inspection Agency |
960 Carling Ave, Bldg 22 C.E.F, Ottawa, ON K1A 0C6 [email protected]
Telephone | Téléphone 613-759-1218
Facsimile | Télécopieur 613-759-1260
Government of Canada | Gouvernement du Canada
[email protected]
5.
Dr. Lutz Elflein
Head of Laboratory / Certified Food Chemist
Tel: +49 (0) 421 65 727 370
Intertek Food Services GmbH
Olof-Palme-Str. 8
28719 Bremen, Germany
Fax: +49 (0) 421 65 727 222
[email protected]
www.applica.de or www.intertek.de
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6.
Mr Wu Bin
Food Laboratory
Animal Plant and Food Inspection Centre
Jiangsu Entry-Exit Inspection and Quarantine Bureau
99 Zhonghua Road
Nanjing 210001, China
tel 00862552345188
Fax 00862552345183
[email protected]
7.
Mr Freddy Thomas (and PT offer)
R&D Authenticity Project Manager
Eurofins Analytics
Rue P.A. Bobierre
BP 42301
F-44323 Nantes Cedex 3 FRANCE
Phone: +33 2 51 83 21 00
Fax: +33 2 51 83 21 11
[email protected]
Web site: www.eurofins.fr
8.
Dr. Fabio Fuselli
Ministry of agricolture food and forrestal policies
Department of Central Inspectorate for Food and Feed Quality protection and Fraud repression
Centrale Laboratory of Rome
Via del Fornetto 85
00149 - Rome (Italy)
Tel. +39 06 55341669
Centr. +39 06 55341641
Fax +39 06 55341691
[email protected]
9.
Dott. Perini Matteo
Laboratorio chimico e consulenza enologica
Sperimentazione agraria, ambientale e forestale
Centro Trasferimento Tecnologico
Via E. Mach n. 2
Fondazione Edmund Mach
38010 San Michele all'Adige (TN)
[email protected]
Tel. 0461615261
Fax. 0461615288
10.
Lesley Chesson
IsoForensics, Inc.
421 Wakara Way, Suite 100
Salt Lake City, UT 84108
Tel. 801-971-6004
http://isoforensics.com
[email protected]
[email protected]
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Appendix D. Cover Letter and Instructions to Participants
Dear Study Participant,
Thank you for participating in the study of modifications to AOAC Method 998.12.
Please ensure that the contents of the parcel have not been damaged during transit.
Complete the enclosed “Study Materials Receipt Form” and e-mail to Jo Marie Cook at
[email protected].
A copy of the study protocol is attached together with a copy of method 998.12 and the
two suggested variations (Appendix A). You should receive three sets of samples, 10
tubes each. Analyze Set 1 using 998.12 as performed in your laboratory. Analyze Set 2
using the filtration step before analysis. Analyze set 3 using the centrifugation / filtration
step before analysis.
Report data using the Excel spreadsheet sent to you via email. There are four sheets to
the workbook; an instruction sheet, a sheet to report the unfiltered analyses, a sheet to
report Set 2 with filtration and a sheet to report Set 3 with centrifugation. In addition to
reporting your test results please enclose a copy of your in-laboratory procedure for the
method or a written description of any variations to 998.12 used in your laboratory.
Please return the report either by email or regular mail BEFORE March 1, 2012.
Your participation in this collaborative study is greatly appreciated.
Sincerely,
Study Directors
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Appendix E. Collaborative Study Materials Receipt Form
Name of Participant:
Please ensure that the items listed below have been received undamaged, insert date of
receipt, and circle the relevant statement:
Date of the receipt
All items have been received undamaged
yes/no
Items are missing/damaged.
yes/no
List missing/damaged items needing replacement, if a whole series is not needed:
I require an additional series of samples
yes/no
Contents of parcel
a) 30 units of samples (10 samples each for three variations of the method; unfiltered,
filtered and centrifuges).
b) A copy of the protocol.
c) An Excel file for reporting results, provided via email
Please e-mail the completed form to:
Jo Marie Cook
Email: [email protected]
Phone: 850-617-7505
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