Development and validation of an ultra high performance liquid chromatography tandem mass spectrometry method for simultaneous determination of sulfonamides, quinolones and benzimidazoles in bovine milk

• A LC–MS/MS method was developed for 46 veterinary drugs in bovine milk.
• A simple pretreatment procedure based on OASIS® MCX SPE had been established.
• Selectivity, linearity, trueness, precision, CCα, and CCβ had been validated.
• The whole method was reliable, convenient and sensitive.

A simple, sensitive and reliable analytical method was developed for the simultaneous determination of 38 veterinary drugs (18 sulfonamides, 11 quinolones and 9 benzimidazoles) and 8 metabolites of benzimidazoles in bovine milk by ultra high performance liquid chromatography-positive electrospray ionization tandem mass spectrometry (UHPLC–ESI-MS/MS). Samples were extracted with acidified acetonitrile, cleaned up with Oasis® MCX cartridges, and analyzed by LC–MS/MS on an Acquity UPLC® BEH C18 column with gradient elution. The method allows such multi-analyte measurements within a 13 min runtime while the specificity is ensured through the MRM acquisition mode. The method was validated according to the European Commission Decision 2002/657/EC determining specificity, decision limit (CCα), detection capability (CCβ), recovery, precision, linearity and stability. For compounds which have MRLs in bovine milk, the CCα values fall into a range from 11 to 115 μg/kg, and the CCβ values fall within a range of 12–125 μg/kg. For compounds which have not MRLs in bovine milk, the CCα values fall into a range from 0.01 to 0.08 μg/kg, and the CCβ values fall within a range of 0.02–0.11 μg/kg. The mean recoveries of the 46 analytes were between 87 and 119%. The calculated RSD values of repeatability and within-laboratory reproducibility experiments were below 11% and 15% for the 46 compounds, respectively. The method was demonstrated to be suitable for the simultaneous determination of sulfonamides, quinolones and benzimidazoles in bovine milk.