Optimizing extraction and concentration methods for LC-MS/MS analysis of veterinary pharmaceuticals in...

This study developed a method for the simultaneous quantification of six potentially environmentally toxic veterinary drugs: benzylpenicillin, acepromazine, flunixin, dexamethasone, ketamine and romifidine, in soils, sediments, equine feces and natural waters. Three methods were compared for their extraction from solid matrices: Ultrasonic extraction (USE), QuEChERS and Accelerated Solvent Extraction (ASE). ASE method was optimized according to temperature and extraction cycles. Quantification was performed by LC-MS/MS. LC and MS parameters were optimized. The method was validated according to French Standard NF T 90-210. Calibration curves exhibited r² ≥ 0.97 from 1 to 100 µg.L^-1. Accuracy was within ± 30%, at 5, 10 and 50 µg.L^-1, except for flunixin at the lowest concentrations. Limit of quantification ranged from 0.1 to 2 µg.L^-1. Both USE and optimized ASE methods provided the highest recoveries, from 20.6% to 115.3% depending on the matrix. This method is suitable for monitoring equine pharmaceutical residues in environmental matrices.