Standard Methods versus Method Criteria - NMKL - · PDF fileNordic Committee on Food Analysis...

Nordic Committee on Food Analysis

Standard Methods versus Method Criteria

AOAC Europe – NMKL – NordVal International Symposium,

Stockholm 2015

Hilde Skår Norli NMKL Secretary General

Contents

Specified standard methods in legislation vs stating method performance criteria that need to be fulfilled

Background for method criteria

Pros & Cons

Established criteria

Standard methods Methods published by Standard Developing Organisations, SDOs: American Oil Chemists Society (AOCS)

AOAC INTERNATIONAL (AOAC)

AOAC Research Institute (AOAC RI)

Association of American Feed Control Officials (AAFCO)

European Committee for Standardization (CEN)

National Food Processors Association

International Association for Cereal Sciences & Technology (ICC)

International Commission for Uniform Methods of Sugar Analysis (ICUMSA)

International Dairy Federation (IDF)

International Federation of Fruit Juice Producers (IFU)

International Federation of Glucose Industries (IFG)

International Office of Cocoa, Chocolate and Sugar Confectionery (IOCCC)

International Organization for Standardization (ISO)

International Wine and Vine Office (OIV)

Nordic Committee on Food Analysis (NMKL)

…..

Standard methods Scope and field of application

Principles

Chemicals/Diluent/Substrates/Reagents

Apparatus/Equipment

Sampling (secondary)

Procedure

● Preparation

● Analysis

Calculation and expression of the results

Reliability of the method

Performance characteristics

M P Criteria is numeric values for the Performance Characteristics

Background for the method criteria

Administratively difficult to change a specified method in legislation

Several methods provide equivalent results

Better, faster and cheaper methods might be available

Pros & Cons for method criteria

More flexible Fit for purpose Resource-saving Quality driven

Easier to enforce Easier to obtain

similar results

Application

Commission Regulation (EC) No

333/2007 of 28 March 2007 laying

down the methods of sampling and

analysis for the official control of

the levels of lead, cadmium,

mercury, inorganic tin, 3-MCPD and

benzo(a)pyrene in foodstuffs.

Guidance document on analytical

quality control and validation

procedures for pesticide residues

analysis in food and feed.

Document No Sanco 12571/2013.

Commission regulation (EC) No

2073/2005 on microbiological

criteria for foodstuffs

- develops harmonized international food standards, guidelines and codes of practice to protect the health of the consumers and ensure fair practices in the food trade

186 Codex Members + 224 Codex Observers 16 commodity committees 10 general committees (CCMAS)

Method Criteria – CCMAS 1992 (NMKL- Sweden lead the project from 2005)

● Reviewed methods for heavy metals

● Criteria included in Codex PM 2008 (working instruction 2009)

The method has to be applicable for the analyte, matrix, and specified level(s) (maximum and/or minimum) (ML).

ML

Level

ML+a ML-a

Elaboration of method criteria

a = 2 ∙ s or 3∙ s

s = standard deviation

Same relation between concentration and standard deviation regardless of analyte, matrix, method principle and time.

Dr. William Horwitz,

1918-2006

Photo: AOAC Int

PRSDR = 2C(-0.15)(%)

RSDR/PRSDR ≤ 2

HorRat

s, at levels ≥ 0.1 mg/kg

s, at levels < 0.1 mg/kg

Prof. Dr. Michael Thompson, Photo: Birkbeck University, London

More recent studies (2000) RSD took a value of 22% for levels below 0.1 mg/kg

Method Performance Criteria - according to Codex Procedural Manual

The criteria is applicable to methods providing results for analyte(s) in a concentration unit.

In Codex the criteria is applicable to type II and type III methods

The criteria are as follow:

Type in ML in mg/kg in the cells below, and the LOD, LOQ,

Applicability: The method has to be applicable for the specified provision, minimum applicable range and precision are calculated for you.spesified commodity and the specified levels(s) (maximum

and/or minium) (ML). The minimum applicable range of the Calculation of criteria for ML ≥ 0.1 mg/kgmethod depends on the specified level (ML) to be assessed, Min. applicable range

and can either be expressed in terms of the reproducibility ML ≥ 0,1 LOD LOQ From To Precision

standard deviation (sR) or in terms of LOD and LOQ. in mg/kg mg/kg mg/kg mg/kg mg/kg RSDR (%)

0,1 0,01 0,02 0,032 0,168 45,2

Minimum For ML ≥ 0.1 mg/kg ; [ML - 3sR, ML+ 3sR] 1 0,1 0,2 0,520 1,480 32,0

applicable range: For ML < 0.1 mg/kg ; [ML - 2sR, ML+ 2sR] 2 0,2 0,4 1,135 2,865 28,8

10 1 2 6,606 13,394 22,6

Limit of For ML ≥ 0.1 mg/kg ; LOD ≤ ML∙1/10 100 10 20 76,003 123,997 16,0

Detection (LOD): For ML < 0.1 mg/kg ; LOD ≤ ML∙1/5 0 0 #DIV/0! #DIV/0! #DIV/0!

0 0 #DIV/0! #DIV/0! #DIV/0!

Limit of Quanti- For ML ≥ 0.1 mg/kg ; LOQ ≤ ML∙1/5 0 0 #DIV/0! #DIV/0! #DIV/0!

fication(LOQ): For ML < 0.1 mg/kg ; LOQ ≤ ML∙2/5 0 0 #DIV/0! #DIV/0! #DIV/0!

0 0 #DIV/0! #DIV/0! #DIV/0!

Precision: For ML ≥ 0.1 mg/kg ; HorRat value ≤2

For ML < 0.1 mg/kg ; RSDR <44%

Calculation of criteria for ML < 0,1 mg/kgRecovery: Conc. Recovery (%) Min. applicable range

100 g/100g 98 – 102 ML < 0,1 LOD LOQ From To Precision

10 g/100g 98 – 102 in mg/kg mg/kg mg/kg mg/kg mg/kg RSDR (%)

1 g/100g 97 – 103 0,01 0,002 0,004 0,006 0,014 44

1 mg/g 95 – 105 0,02 0,004 0,008 0,011 0,029 44

100 mg/kg 90 – 107 0,005 0,001 0,002 0,003 0,007 44

10 mg/kg 80 – 110 0 0 0,000 0,000 44

1 mg/kg 80 – 110 0 0 0,000 0,000 44

100 μg/kg 80 – 110 0 0 0,000 0,000 44

10 μg/kg 60 – 115 0 0 0,000 0,000 44

1 μg/kg 40 – 120

Trueness: |z-score|≤2 proven in pt-scheme or use of crm

These criteria are applicable to:

Rational methods, GC, HPLC, AAS, ICP etc. where concentrations are measured and where Horwitz’and Thompson equation applies.

PRINCIPLES AND GUIDELINES FOR THE ESTABLISHMENT AND APPLICATION OF

MICROBIOLOGICAL CRITERIA RELATED TO FOODS

CAC/GL 21 – 1997 (2013)

4.7 ANALYTICAL METHODS

33. Depending on the microbiological limit (e.g. presence/absence of a specific foodborne pathogen), an appropriate analytical method should be selected. The methods used should be fit for purpose, meaning the method has been validated for relevant performance characteristics (e.g. limit of detection, repeatability, reproducibility, inclusivity, exclusivity). The validation study should be based on internationally accepted protocols and include an interlaboratory study. If not available, a validation should be done by the laboratory applying the method, according to a standardised protocol. 34. The analytical methods specified should be reasonable with regard to complexity, availability of media, equipment, ease of interpretation, time required and costs. 35. The results of testing may be impacted by compositing (i.e. pooling) of sample units prior to analysis. Compositing will affect the final concentration in the tested sample and is not appropriate for enumeration methods of analysis or within three-class sampling plans. Compositing may be considered in the case of presence/absence testing within a two-class sampling plan, as long as it is ensured that the result of testing will not be affected when compared to testing of individual analytical units.