No abstract

No abstract

The presented multi-method was developed for the confirmation of 37 antibiotic substances from the six antibiotic groups: macrolides, lincosamides, quinolones, tetracyclines, pleuromutilines and diamino-pyrimidine derivatives. All substances were analysed simultaneously in a single analytical run with the same procedure, including an extraction with buffer, a clean-up by solid-phase extraction, and the measurement by liquid chromatography tandem mass spectrometry in ESI+ mode. The method was validated on the basis of an in-house validation concept with factorial design by combination of seven factors to check the robustness in a concentration range of 5-50 μg kg(-1). The honeys used were of different types with regard to colour and origin. The values calculated for the validation parameters-decision limit CCα (range, 7.5-12.9 μg kg(-1)), detection capability CCβ (range, 9.4-19.9 μg kg(-1)), within-laboratory reproducibility RSD(wR) (<20% except for tulathromycin with 23.5% and tylvalosin with 21.4 %), repeatability RSD(r) (<20% except for tylvalosin with 21.1%), and recovery (range, 92-106%)-were acceptable and in agreement with the criteria of Commission Decision 2002/657/EC. The validation results showed that the method was applicable for the residue analysis of antibiotics in honey to substances with and without recommended concentrations, although some changes had been tested during validation to determine the robustness of the method.

A new model for the probability of detection (POD curve) for qualitative PCR methods examined in a method validation collaborative study is presented. The model allows the calculation of the POD curve and the limit of detection (LOD 95% ), i.e. the number of copies of the target DNA sequence required to ensure 95 % probability of detection. The between-laboratory variability of the limit of detection is used to derive the betweenlaboratory reproducibility of the PCR method. The model is closely related to the approach for quantitative methods described in ISO 5725.2:2002, and the relative limit of detection approach described in the new standard ISO 16140-2:2014.

A matrix-considering in-house validation concept for analytical methods is presented which takes into account the uncertainty due to matrix-and time-induced deviations. It is based on a variance component model for univariate quantitative measurement data that can be adapted to both screening and confirmation methods and to both zero-tolerance and threshold decisions. The model allows the calculation of critical concentrations for given a-errors and the calculation of the corresponding power function to evaluate the performance of an analytical method. The model is applied to a real-life validation experiment.