ISO/DIS 21568.2

DRAFT INTERNATIONAL STANDARD ISO/DIS 21568.2
ISO/TC 34 Secretariat: MSZT
Voting begins on: Voting terminates on:
2005-05-19 2005-07-19

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION

Produits alimentaires — Méthodes d'analyse pour la détection des organismes génétiquement modifiés et des

This draft International Standard is a draft standard developed within the European Committee for

Standardization (CEN) and processed under the CEN-lead mode of collaboration as defined in the

Vienna Agreement. The document has been transmitted by CEN to ISO for circulation for ISO member

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from non-CEN members, will be considered by the appropriate CEN technical body. Should this DIS be

accepted, a final draft, established on the basis of comments received, will be submitted to a parallel two-

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Foreword............................................................................................................................................................. 4

Introduction ........................................................................................................................................................ 5

1 Scope ..................................................................................................................................................... 5

2 Normative reference ............................................................................................................................. 5

3 Terms and definitions........................................................................................................................... 6

4 Principle................................................................................................................................................. 8

5 Apparatus and equipment.................................................................................................................... 8

6 Sampling of non-packed food products............................................................................................. 8

7 Sampling of packed products – Statistical principles .................................................................... 11

8 Preparation of the analytical sample and the test portion ............................................................. 13

9 Packaging and labelling of laboratory samples .............................................................................. 13

10 Dispatch of laboratory samples ........................................................................................................ 14

11 Sampling report .................................................................................................................................. 14

Annex A (informative) Laboratory sample sizes of different cereals, oilseeds, and derived

products............................................................................................................................................... 16

Annex B (informative) Estimation of the number of particles in 100 mg test portions after

ultracentrifugal milling ....................................................................................................................... 17

Bibliography ..................................................................................................................................................... 18

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The main task of technical committees is to prepare International Standards. Draft International Standards

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International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 21568 was prepared by Technical Committee ISO/TC 34, Agricultural food products, Subcommittee SC ,

and by Technical Committee CEN/TC 275, Food analysis - Horizontal methods in collaboration.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of

Since the first draft prEN ISO 21568 has been circulated for the parallel enquiry in 2003, new scientific

approaches to sampling have been elaborated. The results of a large study on distribution of GMOs in loose

material (bulk agricultural commodities) will be submitted for publication within the next months. Additionally, a

sampling protocol based on these findings was published as a Recommendation by the European

Commission in November 2004. In this study it was proved clearly, that different lots of comparable size

showed a large variety of GMO distribution which is of global relevance. This leads to the conclusion that a

protocol which is based on a distribution assumption can only yield erroneous results. Therefore, it was

necessary to take these new developments into account and to publish a second draft European International

Based on the new scientific evidence the chapter 6 "Sampling of loose food products" of prEN ISO

A new statistical approach was introduced. While the old version suggested a sampling protocol which was

based on a distribution assumption and therefore was based mainly on the size of the laboratory sample to be

analysed, the new protocol is independent of the distribution of GMOs in the lot, and is therefore not affected

by stratification or clustering effects within the lot. In addition to that the new protocol allows an estimation of

the sampling error, which is of great benefit for enforcement authorities as well as for trading companies.

All other changes to the prEN ISO 21568:2003 were introduced following the comments received during the

Correct sampling is an operation that requires the most careful attention. Emphasis should be laid on the

necessity of obtaining a representative sample of the goods under investigation. Accurate analytical work and

interpretation of results are wasted if the sample does not accurately represent the lot from which it is taken.

If ad-hoc sampling of food products is undertaken without applying a sampling strategy and without

considering the lot specific properties, the analytical result is only valid for the sample which has been

By applying sampling frameworks to assess the level of compliance of a given lot of products a certain

number of samples has to be taken, and the result of the analysis can be extended to the whole lot. The use

of sampling plans is the only effective way to make correct statements about the nature, in this case the GMO-

The procedures given in this standard are recognised as good practice and it is strongly recommended that

they be followed whenever practicable. It is recognised that it is difficult to lay down fixed rules to be followed

in every case, and particular circumstances may render some modification of the method desirable.

This standard has been established for food products, but could also be applied to other products, e. g. feed

NOTE In certain areas there are widely recognised trade associations which specify rules for the sampling plans to

be used in contracts under their auspices. In no case will this standard override the rules laid down in such contracts.

This Standard gives guidance for setting up valid sampling strategies for food products that are to be analysed

This draft standard incorporates, by dated or undated reference, provisions from other publications. The

normative references are cited at the appropriate places in the text, and the publications re-listed hereafter.

For dated references, subsequent amendments to or revisions of any of these publications apply to this draft

standard only when incorporated in it by amendment or revision. For undated references the latest edition of

ISO 6644, Flowing cereals and milled products – Automatic sampling by mechanical means

EN ISO 21572:2004, Foodstuffs - Methods of analysis for the detection of genetically modified organisms and

ISO/FDIS 21569, Foodstuffs - Methods of analysis for the detection of genetically modified organisms and

EN ISO 21571:2005, Foodstuffs - Methods of analysis for the detection of genetically modified organisms and

ISO/DIS 24276, Foodstuffs - Nucleic acid based methods of analysis for genetically modified organisms and

A quantity of some commodity delivered at one time and covered by one set of documents. The consignment

NOTE Increments may be tested individually aiming at estimation of the variation of any characteristic throughout a

an actual or conventional object (a defined quantity) on which a set of observations may be made.

one or more items (or a portion of material) selected in some manner from a lot. It is intended to provide

information representative of the lot, and, possibly, to serve as a basis for decision on the lot.

a sample as prepared for sending to the laboratory and intended for inspection or testing

a sample, as prepared for testing or analysis, the whole quantity being used for analysis or testing at one time

the process of selecting one or more representative subsamples from a sample by such means as riffling or

in the estimation of a parameter, the estimation error is the difference between the calculated value of the

part of the total estimation error due to one or several of the following parameters:

the predetermined procedure for the selection, withdrawal and preparation of samples from a lot to yield the

required information so that a decision can be made regarding the acceptance of the lot.

quality level that is the worst tolerable process average when a continuing series of lots is submitted for

NOTE This concept only applies when a sampling scheme with rules for switching and for discontinuation, such as in

NOTE Although individual lots with quality as bad as the acceptance quality limit may be accepted with fairly high

probability, the designation of an acceptance quality limit does not suggest that this is a desirable quality level. Sampling

schemes found in International Standards such as this part of ISO 2859, with their rules for switching and for

discontinuation of sampling inspection, are designed to encourage suppliers to have process averages consistently better

than the AQL. Otherwise, there is a high risk that the inspection severity will be switched to tightened inspection under

which the criteria for lot acceptance become more demanding. Once on tightened inspection, unless action is taken to

improve the process, it is very likely that the rule requiring discontinuation of sampling inspection pending such

the inspection level relates the sample size to the lot size and hence to the discrimination afforded between

NOTE A sampling scheme involves "switching" between normal, tightened and reduced inspection sampling plans,

a limit (value) set by a contract or legal requirements above which a decision shall be made, e.g. regulatory

a sample from which a test result above the specification limit has been obtained.

 homogenisation and reduction of the particle size by appropriate means to form the analytical sample;

Samples shall be representative of the lots from which they are taken. Therefore, as the composition of a lot is

seldom uniform, a sufficient number of increments shall be taken and carefully mixed, thus giving a bulk

sample from which the laboratory sample is obtained by successive divisions or otherwise.

If it is necessary to determine the sampling error, file increment samples should be kept for further analysis.

All sampling operations shall be carried out over a sufficiently short period of time so as to avoid any alteration

Many different types of sampling instruments or equipment are available. Equipment should be chosen as

appropriate for the food products to be sampled and the quantity and containers involved. Examples of

sampling instruments are given in e. g. ISO 13690:1999, ISO 6644:2002. Special care is necessary to ensure

that all sampling apparatus is clean to avoid contamination of the material under investigation.