Validation of a multi-residue method for the determination of several antibiotic groups in honey by LC-MS/MS

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 mu g kg(-1). The honeys used were of different types with regard to colour and origin. The values calculated for the validation parameters-decision limit CC alpha (range, 7.5-12.9 mu g kg(-1)), detection capability CC beta (range, 9.4-19.9 mu g kg(-1)), within-laboratory reproducibility RSDwR (< 20% except for tulathromycin with 23.5% and tylvalosin with 21.4 %), repeatability RSDr (< 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.