Quality criteria for residue analysis and reference materials. Relationship between legal procedures and materials

Summary For qualitative results objective reliability checks are often not present at all or applicable. Interlaboratory ring testing of methods, as sometimes required, showed often not to be applicable simply because enough adequate laboratories are not available. For instance this situation applied to the large number of methods of unclear reliability status, to be used for residue monitoring of hormonal growth promotors (anabolic agents), which are completely banned within the European Communities since January 1988. This impasse was circumvented in 1987 with the formulation by an international group of analytical experts of a set of quality criteria for common analytical techniques like TLC, GC and HPLC (separation), UV, MS and IR spectrometry (detection) and immunoassays (separation and detection). These criteria, now published, are overviewed, as well as the availability of the control and reference materials belonging to them for actual analytical quality control and for validation of laboratories. Although developed for anabolic agents this new approach is applicable in practice for nearly all organic analytes and since very recently also for heavy metals. This approach has clear consequences for the mandatory quality of legislative residue analyses of food stuffs. As based on, amongst others, the combined experience of regulatory residue chemists within the EC, a collection of experimental selectivity indices is presented to rank the required specificity of regulatory residue methods (ranging from within laboratory orientation to international forensic purposes) in an objective way. Finally an estimate is summarized of the financial consequences of the applicable analytical techniques.