Development and Validation of a Multiclass Method for the Analysis of Veterinary Drug Residues in Eggs Using Liquid Chromatography-Tandem Mass Spectrometry

A liquid chromatography tandem-mass spectrometry (LC-MS/MS) method has been developed for the simultaneous determination of 22 veterinary drug residues, belonging to eight classes (coccidiostats, lincosamides, macrolides, tetracyclines, sulfonamides, benzimidazoles, diterpenes, and diaminopyrimidines), in eggs. Chromatographic separations were achieved on an XBridge BEH C18 column (150 × 2.1 mm, 3.5 μm, Waters, USA) maintained at 35 °C. The mobile phase was eluted at 400 μL min−1 in gradient mode between water and methanol/acetonitrile (20:80 v/v), both containing 0.1 % formic acid. The samples were prepared by protein precipitation with acetonitrile without additional cleanup steps. The method was successfully validated according to the Commission Decision 2002/657/EC and was demonstrated to be highly selective and free of matrix and residual effects. The method presented low limits of detection (0.37 to 7.5 μg kg−1) and quantification (1.25 to 20 μg kg−1). For banned substances, the decision limit values (CCα) and detection capability (CCβ) were 0.62–7.5 and 0.65–8.1 μg kg−1, respectively. For substances with a maximum residue limit, the CCα and CCβ values were 2.15–1061.5 and 2.3–1135.9 μg kg−1, respectively. All calibration curves showed excellent correlation (r ≥ 0.99). The recovery of the analytes and internal standards (49.0–103.7 %) was reached with high precision (RSD <8 %). At different concentration levels, the variations in precision and accuracy, in terms of repeatability and in-laboratory reproducibility, were <11 %. The new method is applicable to the routine analysis of commercial egg samples.