Validation of multiresidue methods for veterinary drug residues; related problems and possible solutions

This paper describes problems and possibly solutions encountered when validating a multiresidue method used for analyzing some 100 different veterinary drugs at trace levels in a number of matrices. The validation concept as proposed by the commission decision 2002/657/EC (CD) has been utilized. Slightly deviating approaches had to be developed in order to produce and access the data generated by a multiresidue method. This included concepts, which permit the common validation of banned and regulated substance within the same analytical method. In addition, an alternative calculation of performance parameters (e.g., CCalpha) was developed. This was done in order to ensure correct results even in the absence of measurable bank noise, as typically observed when using high resolution mass spectrometry techniques. The economical aspect of validation (number of required assays) as well as the relative importance of some performance criteria (e.g., CCbeta) have been critically discussed.