TEDINPRENHEDWThe Food and Environment Research Agency

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Protocol for Proficiency Testing Schemes

NOTC

Version 2, January 2012

Part 4 – GeMMA Scheme© Crown Copyright 2012

PREFACE
This Protocol is a series of inter-related documents. This document, Part 4, sets out specific details
for the Genetically Modified Materials Analysis (GeMMA) Scheme. Although this document duplicatessome of the text in Part 1 – Common Principles, it cannot be used in isolation. Part 4 must always
be read in conjunction with Part 1 and vice versa.

VERSION HISTORYThis Protocol was completely revised in 2009, superseding all proficiency testing scheme Protocols
previously published by the Food and Environment Research Agency (previously, Central ScienceLaboratory), i.e. all previous editions of the separate FAPAS and FEPAS Protocols.

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Version 2 of January 2012, this version, supersedes Version 1 of November 2009. The changes areas follows;IN

1.2 Amendments to reflect publication of standard ISO/IEC 17043 and compliance with its
requirementsPR

3.1 Addition of text with regard to test material and homogeneity details in Reports
3.3 and 3.4, change to electronic instructions and reports, not hardcopy

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4.2 Addition of text regarding use of Q-scores

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CONTENTS
1. INTRODUCTION

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1.1 Fera, Defra, PTG and FAPAS

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1.2. Accreditation

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2. ORGANISATION of GeMMA

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2.1. Management System

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3. PARTICIPATION in SCHEMES

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3.2. Dispatch and Receipt of Test Materials

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3.3. Analysis of Test Materials

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3.4. Follow-Up Services

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3.1. Test Material Preparation and Homogeneity

4. PERFORMANCE ASSESSMENTPRIN

4.1. Qualitative assessment4.2. Quantitative assessment

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5. REFERENCES

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1. INTRODUCTION
1.1 Fera, Defra, PTG and FAPASThe Food and Environment Research Agency (Fera) is an Executive Agency of the UK Government
Department for Environment, Food and Rural Affairs (Defra). Fera provides a wide range ofproficiency testing (PT) schemes.
The management of these PT schemes is the sole task of one of many teams within Fera. Knowninternally at Fera as the Proficiency Testing Group (PTG), this team provides Fera’s PT schemesglobally under the brand name of FAPAS PT. The Genetically Modified Materials Analysis (GeMMA)
Scheme is one of these PT schemes.
For the purpose of this Protocol we use FAPAS PT to mean Fera PTG.

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1.2. Accreditation

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GeMMA Scheme is accredited by the United Kingdom Accreditation Service (UKAS). Accreditation isconferred upon GeMMA Scheme in accordance with ISO/IEC 17043:2010 [1].

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The formal schedule of the accreditation can be obtained from the United Kingdom Accreditation
Service (UKAS) web site (Adobe PDF format) [2].

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2. ORGANISATION OF GeMMALL

2.1. Management SystemTRO

The scope of accreditation covers all aspects of the PTs organised by GeMMA:
Qualitative assessments•

Quantitative assessments•

Assessment on w/w basis and haploid genome basis•

Event-specific (e.g. Roundup Ready soya (40-3-2)) and genetic elements (e.g. p35S)•DNA test materials•

Processed and unprocessed matrices

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3. PARTICIPATION IN SCHEMES
3.1. Test Material Preparation and Homogeneity
Subcontracted laboratories are used for test material preparation and homogeneity testing. Rawhomogeneity results are submitted to FAPAS® for statistical evaluation. Homogeneity testing may bequalitative (to confirm absence of an event or detection of contamination) or fully quantitative
depending on the presence of a GM event, where relevant. In either case, homogeneity testing isperformed on ten randomly selected distribution units, in duplicate.
Participants may contact FAPAS PT to request details of test material preparation and homogeneity
testing, where it is pertinent to their assessment. Such details may be released on request, except
Page 4 of 8where this compromises data which is commercial in confidence or where such knowledge isscientifically invalid in the interpretation of assessments.

3.2. Dispatch and Receipt of Test Materials
All GeMMA test materials are sent by standard post. FAPAS® cannot be held responsible for delays
arising from Customs or local postal delivery difficulties.
If GeMMA PTs are subject to delays or cancellations, this is usually due to availability of suitable test
materials or reference materials for testing. Cancellations may also be due to insufficient numbers ofparticipants registering for a test. Participants will be notified by email at the earliest opportunity inthe event of delay or cancellation. Participants registered for a cancelled PT will have the option tochange their registration to another test.

3.3. Analysis of Test Materials

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It is the responsibility of participants to read the instructions (provided electronically via email or
downloaded from the FAPAS PT website, www.fapas.com) and to follow them exactly prior toconducting the actual analysis of the test material. GeMMA Scheme cannot be held responsible forany problems arising from failure to comply with these instructions.

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Example instructions are available on request from GeMMA Scheme.

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After a PT has been completed and values for analyte concentrations assigned, surplus PT test
materials can be used as “quasi-reference” quality control materials. It must be stressed that test
materials are not Certified Reference Materials. However, certified reference materials for the foodanalysis sector are not numerous and surplus FAPAS PT test materials may be the only source of asuitable quality control material.

TROA list of surplus test materials that can be purchased after the test closing date is available from theFAPAS PT website, www.fapas.com. For GeMMA Scheme PTs, surplus test materials may be
extremely limited or not available.

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NMost GeMMA reports issued since 2001 are available for purchase. Prices are available on request.
Participants in all the FAPAS PT schemes have free access to an electronic copy of reports for thosetests for which they have registered. Electronic copies of reports are available on request and acharge will be made for these.

NOIf a participant wishes to obtain advice on any aspect of their performance they should contact FAPAS
PT by email (info@fapas.com) in the first instance. Participants must note that GeMMA Scheme may
offer assistance in the form of a broker service whereby GeMMA Scheme will either anonymously or,subsequent to all parties agreeing to waive their confidentiality, pass on the participant’s inquiry to an
expert laboratory/external advisor.

4. PERFORMANCE ASSESSMENT
4.1. Qualitative assessment
Sourcing uncontaminated material for GM testing is becoming increasingly difficult. It is only for GM
events knowingly added to the matrix during test material preparation that it can confidently be
assumed that the participants’ consensus will be ‘detected’. For all other events the possibility oftrace contamination means that the expected result will be ‘not known’. Qualitative results are
therefore evaluated against the consensus and then may be expressed as either Agreeing or
Disagreeing with the consensus. In addition, where a test material is known to be positive withrespect to GM contamination, results may be expressed as Satisfactory or Not Satisfactory.
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4.2. Quantitative assessment
Quantitative results for GeMMA Scheme PTs are usually expressed as z-scores. The standard
deviations for proficiency assessment are derived from fitness-for-purpose values [4] and expert
opinion (usually the GeMMA Advisory Committee). Occasionally, Q-scores may be issued instead,where a fitness-for-purpose RSDR is not available. See Part 1 of this Protocol and the International
Harmonised Protocol for a description of the use of Q-scores [3]. Q-scores present the bias ofreported results taking no account of the standard deviation for proficiency. Since bias cannot bepredicted, no satisfactory range can be given. Q-scores should NOT be interpreted in the same way
as z-scores. Q-scores would be given purely for presentational purposes and for information only.
Quantitative GeMMA results are log transformed. The rationale for this approach is documented [4,5, 6] and, hence, the formula for calculation of z-scores is modified to;(log10 x − log10 xa )

σp

where

x is the participant’s reported resultTEDz=xa is the assigned value

σp is the standard deviation for the proficiency test.

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Quantitative results have historically been submitted on a percentage weight-for-weight (% w/w)
basis. Under EU Commission Recommendation No. 2004/787/EC [7], the percentage of GM-DNA has
been defined under section II DEFINITIONS, item (h), as: the percentage of GM-DNA copy numbers
in relation to target taxon specific copy numbers calculated in terms of haploid genomes. This EUCommission Recommendation is for guidance purposes only, therefore, the submission of resultsexpressed in a percentage (%) on a haploid genome basis is optional and not mandatory. GeMMA
Scheme therefore accepts results on either % w/w or % haploid genome basis and treats theseresults separately.

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5. REFERENCES
ISO/IEC 17043:2010, Conformity assessment – General requirements for proficiency testing.

2

http://www.ukas.com/about-accreditation/accredited-bodies/proficiency-testing-organisations.asp

3Thompson, M., Ellison, S.L.R. and Wood R., 2006, The International Harmonised Protocol for theProficiency Testing of Analytical Chemistry Laboratories, Pure Appl. Chem., 78 (1), 145-196.

4Powell, J. and Owen, L., 2002, Reliability of Food Measurements: The Application of Proficiency
Testing to GMO Analysis, Accred. Qual. Assur., 7, 392-402.

5

Analytical Methods Committee, 2004, GMO Proficiency Testing: Interpreting z-scores derived
from log-transformed data, RSC, AMC Technical Brief, No.18, December 2004.

6Thompson, M., et al, 2006, Scoring in GMO Proficiency Tests based on log-transformed results,J. AOAC Int., 89 (1), 232-239.

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Commission Recommendation No. 2004/787/EC of 4 October 2004 on technical guidance forsampling and detection of genetically modified organisms and material produced from geneticallymodified organisms as or in products in the context of Regulation (EC) No 1830/2003, Official
Journal, L 348, 24/11/2004, 0018-0026.

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FAPAS GeMMA Scheme
Proficiency Testing GroupThe Food and Environment Research Agency
Sand Hutton, YorkYO41 1LZ
UK
Tel:
Fax:
e-mail:web:+44 (0)1904 462100+44 (0)1904 462040
info@fapas.com
www.fapas.com

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