Optimization of multiple reaction monitoring mode for the trace analysis of veterinary sulfonamides by LC-MS/MS.

One of the oldest groups of veterinary chemotherapeutic agents, sulfonamides have been widely used for more than 50 years, thanks to their low cost and their broad spectrum of activity in preventing or treating bacterial infections. Nowadays, those compounds are regularly detected in a wide variety of environmental samples, including natural waters, sediments and soils. Since the environmental concentrations of sulfonamides are usually very low and their occurrence multicomponental, their determination in these matrices still pose significant analytical problems. The present paper describes the optimization of ESI-MS/MS parameters and the chromatographic separation of 12 sulfonamides commonly used in veterinary medicine. The methodology developed in this study, unlike many others, satisfied the requirements of EU Commission Decision 2002/657/EC, which defines the criteria for both screening and confirmatory methods with respect to drug residues on the basis of identification points. Each MRM transition was tested not only for the qualitative but also for the quantitative analysis of sulfonamides. The method was validated for its analytical performance parameters and applied to the determination of those compounds in soil samples.