Validation; 2002/657/EC; Detection capability; Precision; SUMMARY The European decision 2002/657/EC imposes that each analytical method used for official control of foodstuffs is validated. The methodologies described in the ISO 5725 and the ISO 11843 standards are used to set up an experimental validation plan that minimizes the number of samples without increasing the uncertainty of the performance characteristics. At each level (0.5, 1 and 1.5 times the MRL) minimum 8 samples are analyzed on 3 different days. Recovery, repeatability, within-lab reproducibility, CCalfa and CCbeta are determined simultaneously. The uncertainty of each performance characteristic is not increased since the degrees of freedom are equal or higher compared to the conventional validation plan. Only 24 samples (27 samples for a balanced design) are needed with this validation strategy. INTRODUCTION Validation of the analytical method is required for every method used for the official control of foodstuffs. The validation procedure and the performance characteristics for these methods are defined in the European Decision 2002/657/EC. (1) A performance characteristic is a quality measure of the analytical method. The performance characteristics specificity, accuracy, trueness, precision, repeatability, reproducibility, recovery, detection capability and ruggedness are required by the latter decision. To obtain these characteristics a lot of analytical work has to be performed in the laboratory. It is generally known that validation of analytical methods is a time and money consuming activity. The validation effort can easily be reduced by introducing a smaller number of samples. However this will enlarge the uncertainty associated with the performance characteristic. The increase in uncertainty of the performance characteristics can be avoided by combining the validation experiments. The aim of this paper is to develop a validation plan for a quantitative confirmatory method. A maximum of performance characteristics should be obtained with a minimum of samples without an increase of the uncertainty. EXPERIMENTAL
