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.