Ruggedness testing and validation of a practical analytical method for >100 veterinary drug residues in bovine muscle by ultrahigh performance liquid chromatography-tandem mass spectrometry.

In this study, optimization, extension, and validation of a streamlined, qualitative and quantitative multiclass, multiresidue method was conducted to monitor >100 veterinary drug residues in meat using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Optimization centered on extensive ruggedness evaluation of the method. Various clean-up sorbents were tested and the amount of co-extractives were weighed, matrix effects were measured using post-column infusion of representative analytes, the effect of extract dilution before injecting was studied, and analyte recoveries and reproducibilities were determined. In order to extend our previous method, more drug analytes were added that possessed a wider range of chemical properties, and a re-appraisal of different types of C18 in dispersive solid-phase extraction clean-up and mobile phases in UHPLC-MS/MS was done. Ultimately, end-capped C18 and post-column infusion of ammonium formate as an ionization enhancer for the late-eluting anthelmintics were found to give improved qualitative results for greater analytical scope. A multi-day, multi-analyst validation demonstrated that the final method is suitable for screening of 113 analytes, identifying 98 and quantifying (recoveries between 70-120% and RSD<25%) 87 out of the 127 tested drugs at or below US regulatory tolerance levels in bovine muscle.