RECOMMENDATIONS FOR METHODS OF ANALYSIS AND SAMPLING (Agenda Item 7)

(a) Single-laboratory Validation of Methods of Analysis and Sampling
(b) Revision of the List of Methods of Analysis for Pesticide Residues

151. The Chairperson of the ad hoc Working Group of Methods of Analysis and Sampling, Dr P. van Zoonen (The Netherlands), presented the report of the Group.

(a) Single-laboratory Validation of Methods of Analysis and Sampling[34]

152. The Committee noted that a Joint AOAC/FAO/IAEA/IUPAC Expert Consultation on Single-Laboratory Validation on Analytical Methods for Trace-Level Concentrations of Organic Chemicals[35] had been held in Miskolc, Hungary, in November 1999 as a follow-up action to the Joint FAO/IAEA Expert Consultation on Validation of Analytical Methods for Food Control held in Vienna in 1997. The Committee was informed of the key concepts for single-laboratory method validation developed by the Miskolc Consultation. These concepts included the identification of performance verification (Internal Quality Assurance) as an important continuing aspect of the validation process and consequently the concept of the Lowest Calibrated Level (LCL) was introduced. The Committee noted the need for the classification “screening methods” in addition to quantitative methods. It was agreed that these concepts could be used for enhancing harmonization between this Committee and the CCRVDF and should form the basis for a new set of criteria for the assessment of the suitability of analytical methods for Codex purposes.

153. The Committee agreed that:

• Methods appropriately validated in a single laboratory can be considered suitable for determination of compliance with Codex MRLs in addition to methods that have been validated through collaborative study;
• Where practicable, the single-laboratory method validation requirements of the CCPR should be harmonised with those of other Codex committees;
• A paper should be prepared by a drafting group (Australia, Brazil, Canada, France, Germany, India, The Netherlands, United Kingdom, the USA and GCPF), led by The Netherlands, describing appropriate performance parameters and criteria for the assessment of the suitability of analytical methods for CCPR purposes. The paper should be circulated for comments, in particular, on the proposed requirements for method validation. Noting that a similar paper would be prepared for consideration by the CCRVDF at its next session, the Committee invited those countries involved in the drafting groups of both Committees to ensure harmonization and coordination between these activities;
• Approval should be sought from the Executive Committee to initiate new work on the amendments to the Guidelines on Good Laboratory Practice in Pesticide Residue Analysis and the Introduction section of the Recommended Methods of Analysis for Pesticide Residues to accommodate reference to single-laboratory method validation and suitability of methods validated in a single laboratory;
• Availability of suitable reference materials is critical to support validation of analytical methods used for determining compliance with Codex MRLs; and
• Mechanisms should be developed to facilitate dissemination of information on analyte stability and other data that can assist the analyst in judging the performance of the methods used.

154. The Committee endorsed the view of the Working Group that although the verification of extraction efficiency could ideally be determined by experiments with radio-labelled compounds, a limited number of laboratories had the facilities to conduct these experiments. Therefore alternative approaches, e.g., through proficiency testing, robustness experiments or multiple extraction schemes, might be appropriate.

(b) Revision of the List of Methods of Analysis for Pesticide Residues[36]

155. The Committee agreed that the list should be revised after a full agreement was reached on the parameters and criteria applied to methods. The Committee agreed to the following procedure for revising the list:

(i) The circular letter referred to in para. 153 above should also request relevant validation information on methods of analysis for some of those compounds that entered the Codex system in recent years. This information should be provided in accordance with the criteria to be developed by the drafting group mentioned above and to be included in the same circular letter.

(ii) Subsequently an assessment should be made of the validation data received.

(iii) If a suitable list of parameters and criteria is developed to support the selection of recommended methods, the existing list of recommended methods should be revised accordingly.