1. GENERAL CRITERIA FOR THE SELECTION OF SINGLE-LABORATORY VALIDATED METHODS OF ANALYSIS (TO BE INCLUDED AFTER THE GENERAL CRITERIA)
Inter-laboratory validated methods are not always available or applicable, especially in the case of multi-analyte/multi substrate methods and new analytes. The criteria to be used to select a method are included in the General Criteria for the Selection of Methods of Analysis. In addition the single-laboratory validated methods must fulfill the following criteria:
i. the method is validated according to an internationally recognized protocol (e.g. those referenced in the harmonized IUPAC Guidelines for Single-Laboratory Validation of Methods of Analysis)
ii. the use of the method is embedded in a quality system in compliance with the ISO/IEC 17025: 1999 Standard or the OECD Principles of Good Laboratory Practice;
The method should be complemented with information on accuracy demonstrated for instance with:
- regular participation in proficiency schemes, where available;
- calibration using certified reference materials, where applicable;
- recovery studies performed at the expected concentration of the analytes;
- verification of result with other validated method where available
2. Guidelines for the Inclusion of Specific Provisions in Codex Standards and Related Texts
Principles for the Establishment of Codex Methods of Analysis
Specificity: deleted
Selectivity: Selectivity is the extent to which a method can determine particular analyte(s) in mixtures or matrices without interferences from other components of similar behaviour.
Selectivity is the recommended term in analytical chemistry to express the extent to which a particular method can determine analyte(s) in the presence of interferences from other components. Selectivity can be graded. The use of the term specificity for the same concept is to be discouraged as this often leads to confusion.
Accuracy (as a concept) and Accuracy (as a statistic) to be replaced with the following definition:
Accuracy: The closeness of agreement between a test result and the accepted reference value.
Note:
The term accuracy, when applied to a set of test results, involves a combination of random components and a common systematic error or bias component.
Trueness: The closeness of agreement between the average value obtained from a series of test results and an accepted reference value.
Notes:
1 The measure of trueness is usually expressed in terms of bias.
2 Trueness has been referred to as “accuracy of the mean”. This usage is not recommended.
Selectivity: Selectivity is the extent to which a method can determine particular analyte(s) in mixtures or matrices without interferences from other components of similar behaviour.
Selectivity is the recommended term in analytical chemistry to express the extent to which a particular method can determine analyte(s) in the presence of interferences from other components. Selectivity can be graded. The use of the term specificity for the same concept is to be discouraged as this often leads to confusion.
