CEN/TR 17421:2019

SLOVENSKI STANDARD
01-december-2019
Krma: metode vzorčenja in analize - Priporočila za organizacijo in vrednotenje
medlaboratorijskih primerjalnih shem za multirezidualne analizne metode
Animal feeding stuffs: Methods of sampling and analysis - Recommendations for the
organization and evaluation of collaborative studies for multi-analyte methods of analysis
Futtermittel - Probenahme- und Untersuchungsverfahren - Ringversuchsvorgaben für
Multi-Analyt-Untersuchungsverfahren
Aliments pour animaux : Méthodes d’échantillonnage et d'analyse - Recommandations
pour l’organisation et l’évaluation des études comparatives interlaboratoires utilisant des
méthodes d'analyses multianalytes
Ta slovenski standard je istoveten z: CEN/TR 17421:2019
ICS:
65.120 Krmila Animal feeding stuffs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TR 17421
TECHNICAL REPORT
RAPPORT TECHNIQUE
September 2019
TECHNISCHER BERICHT
ICS 65.120
English Version
Animal feeding stuffs: Methods of sampling and analysis -
Recommendations for the organization and evaluation of
collaborative studies for multi-analyte methods of analysis
Aliments pour animaux : Méthodes d'échantillonnage Futtermittel - Probenahme- und
et d'analyse - Recommandations pour l'organisation et Untersuchungsverfahren - Ringversuchsvorgaben für
l'évaluation des études comparatives interlaboratoires Multi-Analyt-Untersuchungsverfahren; Deutsche und
utilisant des méthodes d'analyses multianalytes Englische Fassung prEN 00327126:2018

This Technical Report was approved by CEN on 9 September 2019. It has been drawn up by the Technical Committee CEN/TC
327.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 17421:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Prerequisites to a collaborative study . 5
5 Design of the collaborative study . 6
6 Data collection, evaluation and interpretation . 9
7 Final collaborative study report . 10
8 Implementation of the results of the validation study in the standard . 11
Bibliography . 12
European foreword
This document (CEN/TR 17421:2019) has been prepared by Technical Committee CEN/TC 327 “Animal
feeding stuffs: Methods of sampling and analysis”, the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2020, and conflicting national standards shall be
withdrawn at the latest by March 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Introduction
One of the important parts of the development of a European standard method of analysis is the
collaborative study to validate this method. This study should provide sufficient information whether the
method is fit for its intended purpose and on the performance characteristics that can be expected in
practice. At the same time the necessary effort for the study organizer and the participating laboratories
should be kept at a minimum. This guideline is to provide support to those involved in designing,
executing, and evaluating such studies.
General information on how to do this is already described in a number of different documents of which
a non-exhaustive list can be found at the end of this document in the Bibliography. CEN/TC 327
recommends that for all collaborative studies executed under the auspices of its working groups the
“AOAC guidelines for collaborative study procedures to validate characteristics of a method of analysis”
[1] is used as the primary source of information for any issues not dealt with in this document. Other
relevant documents have been published by ISO [2], IUPAC [3], and EURACHEM [4].
In addition, this document presents prerequisites related to the acceptance of single-laboratory
validation studies, the preparation of the standard operating procedure, and the proper implementation
of the analytical method by the participating laboratories to ensure the transferability of the method.
The development of methodologies such as GC-MS, LC-MS, ICP-MS, etc. has made it possible to determine
multiple analytes in a single analysis (i.e. same extraction, clean up, and determination procedure). The
specificities of such multi-analyte methods need to be taken into account when organizing the
collaborative trial in order to minimize the workload required while covering the necessary
analyte/matrix/concentrations combinations.
1 Scope
This document provides guidance to study organizers involved in designing, executing and evaluating
collaborative studies for multi-analyte methods developed by the various working groups of the
CEN/TC 327 “Animal feeding stuffs: Methods of sampling and analysis”. The main goal of such studies is
to determine the reproducibility standard deviations for the analytes investigated in the selected
matrices. They are calculated from the repeatability and the between-laboratory standard deviations
determined from the study data. An additional goal may be the determination of the trueness (whenever
possible).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
material
certain combination of analyte, matrix and concentration
3.2
matrix
components of the test material other than the analyte
[SOURCE: IUPAC Gold book [5]]
Note 1 to entry: The term “matrix” may stand synonymously for “matrix-category”.
4 Prerequisites to a collaborative study
4.1 General
Collaborative studies for multi-analyte methods require a lot of effort from the study organizer and the
participants. They may require extensive personnel and material resources. Every effort should be made
to ensure the success of the study.
4.2 Performance characteristics from single-laboratory validation
The fitness-for-purpose of the method of analysis that is to be standardized needs to be demonstrated by
a comprehensive and well-designed single-laboratory validation study. This study is to be executed
according to the internationally agreed rules, covering relevant combinations of analytes, matrices and
concentrations.
A single-laboratory validation study should provide for each analyte the following performance
characteristics: selectivity, working range, analytical sensitivity, precision (repeatability and
intermediate precision), and trueness. The estimation of such performance characteristics is described
in international documents [4] [6]. Only when the low end of the working range approaches very low
levels, and if deemed necessary by the responsible TC working group, the limits of detection and/or
quantification should explicitly be determined following accepted guidance [7].
Materials with reliable reference values – covering the concentration range of interest – should be used
for the estimation of trueness.
4.3 Standard operating procedure
Before starting a collaborative study a draft of the standard operating procedure (SOP) shall be available.
It shall be clear, concise, unambiguous, and complete. It shall be understandable to the members of the
working group and the potential participants. The quality of this SOP is crucial to the success of the study.
All relevant details of the analytical method shall be described. Critical steps should be identified, clearly
addressed, and acceptable ranges of variation shall be defined. The draft SOP should comply with the
structure and format specified in ISO 78-2 [8], including instructions on how to calculate and express test
results.
Prior to implementation, the SOP should be reviewed by the responsible TC working group. Suggested
comments and improvements – also from participating laboratories of a possible pre-trial – should be
implemented in the final version of the SOP.
Any change of technical details in the SOP after finishing the validation study might invalidate the data
collected during that study.
5 Design of the collaborative study
5.1 Test materials
5.1.1 Selection of test materials
The adequate selection of test materials (different analyte/matrix/concentration combinations) for the
collaborative study is critical as it ultimately defines the applicability and working range of the method.
The investigated test materials shall be representative of real samples, in terms of composition, matrix,
target species, concentration, and interferences.
It would be ideal if:
— The concentration levels in the test materials covered the working range of the method for each
analyte/matrix-category combination as much as possible.
— Several different concentration levels were validated when for one matrix-category a broader
concentration range (e.g. larger two orders of magnitude) can occur in practice.
— Materials of a slightly lower and slightly larger concentration were included bracketing
concentration levels that are tolerance limits or specification levels.
However, in the case of the validation of multi-analyte methods realistic, yet suitable (minimum of five),
numbers of materials are required to minimize the workload.
Typically, an appropriate design should take into account matrix similarities, target analyte
concentration ranges (at least around the tolerance and/or legislative limits), matrix interferences and
instrumental specificities (e.g. ionization suppression or enhancement in LC-MS/MS).
While all matrices should be represented, the variety of matrices should be given preference over the
levels of concentrations in each matrix. This may result in complex test materials. If not all the analytes
that the method may be able to detect will appear at the same time in the same real test material then it
is not necessary to have all analytes in each validation test material. Preferably, every analyte should
appear at least five times in the validation test materials. If this is not possible, a lower number should be
agreed upon by the responsible TC working group.
If the scope of the method includes the determination of levels close to the detection limit, a blank
material should be included (when available).
In the case of mycotoxins or plant toxins, test materials with naturally incurred analytes should be used
if available. This may also be the case e.g. for feed additives, pesticides or process contaminants. If such
incurred test materials are not available at all or not at the required concentration they should be
prepared by fortifying (“spiking”) an existing material, e.g. analyte-free, missing analytes or with analytes
at too low concentrations. The procedure to be followed should be defined by the study organizer and
applicability be verified during the single-laboratory validation study. The resulting test material needs
to mimic the behaviour of real materials.
The concentration for a given analyte in a test material may be
...