Determination of 20 coccidiostats in egg and avian muscle tissue using ultra high performance liquid chromatography–tandem mass spectrometry

A quantitative, comprehensive multiresidue method which includes 20 coccidiostat residues has been developed. The method described uses a simple one-step liquid extraction with acetonitrile to isolate analytes from both the polyether ionophore and chemical classes of coccidiostats. Subsequent to a further concentration step, samples were analysed via UHPLC–MS/MS. The method was validated according to the Commission Decision 2002/657/EEC in egg and avian muscle. The method permitted quantitative confirmation for 13 compounds below target concentrations, and screening for a further 7 compounds. Within-laboratory repeatability gave accuracy values in the range of 68–129%, while reproducibility ranged between 75 and 123%. Calibration ranges were typically 1–50 μg kg−1, although higher ranges were used for dinitrocarbanilide, imidocarb and toltrazuril residues. A regression coefficient (R2) value of greater than 0.98 was obtained for all analytes. Precision results ranged from 2.3 to 19.7% CV for egg and from 2.6 to 23.6% CV in muscle. CCα was in the range from 1.13 μg kg−1 (clopidol) to 179 μg kg−1 (lasalocid) in egg. In muscle, CCα ranged from 2.25 μg kg−1 (aprinocid) to 4579 μg kg−1 (dinitrocarbanilide). CCβ was from 1.29 μg kg−1 (clopidol) to 209 μg kg−1 (lasalocid) in egg, and 2.58 μg kg−1 (arprinocid) to 6060 μg kg−1 (dinitrocarbanilide) in muscle. Limits of quantification were 1 μg kg−1 for all compounds, except imidocarb and dinitrocarbanilide (10 μg kg−1), and toltrazuril and metabolites (50 μg kg−1).