Animal feeding stuffs: Methods of sampling and analysis - Recommendations for the organization and evaluation of collaborative studies for multi-analyte methods of analysis

This document gives guidance to those involved in designing, executing and evaluating interlaboratory comparison studies for multi-analyte methods of analysis, developed by CEN/TC 327 “Animal feeding stuffs: Methods of sampling and analysis” and its working groups.
For the validation of multi-analyte methods their particularities must be considered which might necessitate deviations from the prescribed validation protocols. This study provides information whether the method is fit for its purpose and which performance can be expected in practical work while at the same time keeping the necessary effort for the study organizer and the participating laboratories minimal.
Next to the abovementioned aspects regarding interlaboratory comparison studies, this document also gives guidance on the preceding steps, viz. in-house validation and preparation of the method protocol. Guidance is also given on the transferability of the method protocol and the familiarization with the method protocol through a training study, elements that – depending on the specific method – could be included in the design of the study.

Futtermittel - Probenahme- und Untersuchungsverfahren - Ringversuchsvorgaben für Multi-Analyt-Untersuchungsverfahren

Dieses Dokument enthält eine Anleitung für Organisatoren von Studien, die an der Konzeption, Durchführung und Auswertung von Ringversuchen für Multi Analyt Verfahren beteiligt sind, die von den verschiedenen Arbeitsgruppen des CEN/TC 327 „Futtermittel — Probenahme  und Untersuchungs¬verfahren“ entwickelt wurden. Das Hauptziel solcher Studien ist es, die Vergleichstandardabweichungen für die in den ausgewählten Matrices untersuchten Analyte zu bestimmen. Diese werden aus der Wiederholpräzision und den aus den Versuchsdaten ermittelten Standardabweichungen zwischen den Laboratorien berechnet. Ein weiteres Ziel kann die Bestimmung der Richtigkeit sein (wo immer möglich).

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

Le présent document fournit des recommandations à l’attention des organisateurs d’études impliqués dans la conception, l’exécution et l’évaluation d’études comparatives interlaboratoires pour des méthodes multianalytes développées par les divers groupes de travail du CEN/TC 327 « Aliments des animaux : Méthodes d’échantillonnage et d’analyse ». Le principal objectif de ces études est de déterminer les écarts-types de reproductibilité pour les analytes examinés dans les matrices sélectionnées. Ils sont calculés à partir de la répétabilité et des écarts-types entre laboratoires, déterminés à partir des données de l’étude. Un but supplémentaire peut être la détermination de la justesse (lorsque c’est possible).

Krma: metode vzorčenja in analize - Priporočila za organizacijo in vrednotenje medlaboratorijskih primerjalnih shem za multirezidualne analizne metode

Ta dokument podaja napotke vsem, ki sodelujejo pri načrtovanju, izvajanju in vrednotenju medlaboratorijskih primerjalnih shem za multirezidualne analizne metode, ki jih je razvil odbor CEN/TC 327 »Krma za živali: metode za vzorčenje in analizo« ter njegove delovne skupine.
Za validacijo multirezidualnih analiznih metod je treba upoštevati njihove posebnosti, ki bi lahko zahtevale odstopanja od predpisanih validacijskih protokolov. Ta shema podaja informacije, ali je metoda primerna za njen namen in kakšno učinkovitost je mogoče pričakovati pri praktičnem delu, hkrati pa zagotavlja, da so potrebni napori organizatorja sheme in sodelujočih laboratorijev minimalni.
Ta dokument poleg zgoraj omenjenih vidikov medlaboratorijskih primerjalnih shem daje tudi smernice za predhodne korake, tj. interno potrjevanje in pripravo protokola metode. Podane so tudi smernice za prenosljivost protokola metode in seznanjanje s protokolom metode s pomočjo sheme o usposabljanju, elementih, ki bi (odvisno od metode) lahko bili vključeni v zasnovo sheme.

General Information

Status
Published
Public Enquiry End Date
24-May-2019
Publication Date
06-Nov-2019
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
16-Oct-2019
Due Date
21-Dec-2019
Completion Date
07-Nov-2019

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SLOVENSKI STANDARD
SIST-TP CEN/TR 17421:2019
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
SIST-TP CEN/TR 17421:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST-TP CEN/TR 17421:2019
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SIST-TP CEN/TR 17421:2019
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.
---------------------- Page: 3 ----------------------
SIST-TP CEN/TR 17421:2019
CEN/TR 17421:2019 (E)
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

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SIST-TP CEN/TR 17421:2019
CEN/TR 17421:2019 (E)
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.
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SIST-TP CEN/TR 17421:2019
CEN/TR 17421:2019 (E)
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.
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SIST-TP CEN/TR 17421:2019
CEN/TR 17421:2019 (E)
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

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SIST-TP CEN/TR 17421:2019
CEN/TR 17421:2019 (E)

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

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SIST-TP CEN/TR 17421:2019
CEN/TR 17421:2019 (E)

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 outside of the working range. While the

SOP should clearly indicate the working range for each analyte and the test portion size to be used, it

should also include provisions for possibly different test portion size or an additional dilution in such

cases.

When the SOP contains various modular experimental paths (e.g. different extraction approaches for

different matrices), which participating laboratories may select from, the selection of test materials shall

be such that for each module a sufficient variety of test materials is included.
5.1.2 Production of test units

The total amount of bulk material to be prepared depends on the number and size of test units required.

The test unit size depends on the test portion size, and whether laboratories should be able to repeat the

sample preparation. The test unit number depends on the number of test units per laboratory (e.g. blind

duplicates), and the anticipated number of participating laboratories.

Once the total number of test units has been determined, an additional 10 % of units should be for

...

SLOVENSKI STANDARD
kSIST-TP FprCEN/TR 17421:2019
01-julij-2019
Krma: metode vzorčenja in analize - Priporočila za organizacijo in vrednotenje
medlaboratorijskih študij večanalitskih metod za analizo

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; Deutsche und Englische Fassung prEN
00327126:2018

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: FprCEN/TR 17421
ICS:
65.120 Krmila Animal feeding stuffs
kSIST-TP FprCEN/TR 17421:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
kSIST-TP FprCEN/TR 17421:2019
---------------------- Page: 2 ----------------------
kSIST-TP FprCEN/TR 17421:2019
FINAL DRAFT
TECHNICAL REPORT
FprCEN/TR 17421
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
May 2019
ICS
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

l'évaluation des études comparatives interlaboratoires fÃ1/4r Multi-Analyt-Untersuchungsverfahren;

utilisant des méthodes d'analyses multianalytes Deutsche und Englische Fassung prEN 00327126:2018

This draft Technical Report is submitted to CEN members for Vote. 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.

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

aware and to provide supporting documentation.

Warning : This document is not a Technical Report. It is distributed for review and comments. It is subject to change without

notice and shall not be referred to as a Technical Report.
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. FprCEN/TR 17421:2019 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
kSIST-TP FprCEN/TR 17421:2019
FprCEN/TR 17421:2019 (E)
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

4.1 General ................................................................................................................................................................ 5

4.2 Performance characteristics from single-laboratory validation ................................................... 5

4.3 Standard operating procedure ................................................................................................................... 6

5 Design of the collaborative study .............................................................................................................. 6

5.1 Test materials ................................................................................................................................................... 6

5.1.1 Selection of test materials ............................................................................................................................ 6

5.1.2 Production of test units ................................................................................................................................. 7

5.1.3 Characterization of test units ..................................................................................................................... 7

5.2 Experimental design ...................................................................................................................................... 8

5.3 Pre-trial .............................................................................................................................................................. 8

5.4 Validation phase .............................................................................................................................................. 9

6 Data collection, evaluation and interpretation .................................................................................... 9

6.1 Collection ........................................................................................................................................................... 9

6.2 Evaluation .......................................................................................................................................................... 9

6.3 Interpretation ................................................................................................................................................... 9

7 Final collaborative study report ............................................................................................................. 10

8 Implementation of the results of the validation study in the standard .................................... 11

8.1 General ............................................................................................................................................................. 11

8.2 Title ................................................................................................................................................................... 11

8.3 Scope ................................................................................................................................................................. 11

8.4 Statistical data ............................................................................................................................................... 11

8.5 Additional information .............................................................................................................................. 11

Bibliography ................................................................................................................................................................. 12

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kSIST-TP FprCEN/TR 17421:2019
FprCEN/TR 17421:2019 (E)
European foreword

This document (FprCEN/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 document is currently submitted to the vote.

This document has been prepared under a mandate given to CEN by the European Commission and the

European Free Trade Association.
---------------------- Page: 5 ----------------------
kSIST-TP FprCEN/TR 17421:2019
FprCEN/TR 17421:2019 (E)
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.
---------------------- Page: 6 ----------------------
kSIST-TP FprCEN/TR 17421:2019
FprCEN/TR 17421:2019 (E)
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 http://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

---------------------- Page: 7 ----------------------
kSIST-TP FprCEN/TR 17421:2019
FprCEN/TR 17421:2019 (E)

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 metarials 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

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kSIST-TP FprCEN/TR 17421:2019
FprCEN/TR 17421:2019 (E)

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. analytefree, missing analytes or with analytes

at too low concentrations.
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