NMKL validation

In contrast to many other validation protocols, the description of the NMKL validation process starts with the protocol of planned validation. This protocol should include, e.g., the needs of the client, available equipment, the chemical form in which the analyte occurs (i.e., in pesticide analysis the residue definition), matrix types, the availability of reference materials and the working range. Consequently, an extra paragraph is dedicated to the requirements for the documentation of validation results, which refers to the rules in Section 5.4.4 of EN 45001 (amended by ISO 17025). 

Komit6 for Levnedsmidler (NMKL)]. The standard presents a universal validation approach for chemical analytical methods in the food sector. This includes methods for the main constituents and also for trace components. Therefore, the NMKL procedure focuses on primary validation parameters, such as specificity, calibration, trueness, precision, LOD or LOQ and does not refer to special requirements of pesticide residue analysis. 

Verification implies that the laboratory investigates trueness and precision in particular. Elements which should be included in a full validation of an analytical method are specificity, calibration curve, precision between laboratories and/or precision within laboratories, trueness, measuring range, LOD, LOQ, robustness and sensitivity. The numbers of analyses required by the NMKL standard and the criteria for the adoption of quantitative methods are summarized in Table 10. 

In the NMKL procedure, verification is an important aspect of continuous documentation of the quality of on-going analyses performed with validated methods. 

Table 10 Summary of NMKL parameters and criteria for validation of procedures involved in a quantitative method ...

Any validation and verification work performed must always be documented in such a way that the results can be checked and the scope of a method is clear. International standards, e.g., ISO 17025, contain separate sections regarding documentation, which should be observed. The NMKL procedure on method validation states that It is of particular importance that the report includes all raw data from the experimental work, or references to where such data can be found . In some circumstances this complete documentation is impractical. Even where it is practical, it is usually impossible to publish these results together with the methods. 

Nordic Committee on Food Analysis, NMKL Procedure No. 4, Validation of Chemical Analytical Methods, NMKL General Secretariat, Finland (1996). 

The NMKL (1997c) described an enzymatic method for determination of starch and glucose in foods that was validated in a collaborative study. Starch was... 

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