Determination of eprinomectin in bovine urine and Feces using HPLC with fluorescence detection

Eprinomectin is a novel and potent antiparasitic animal health drug. An analytical procedure for the determination of EPR in bovine urine and feces has been developed. The urine sample was centrifuged and alkalized with ammonia following solid phase extraction. The fecal sample was extracted with acetonitrile, defatted with hexane, cleaned-up using C18 cartridge. All samples were analyzed by high performance liquid chromatography with fluorescence detection after derivatization with N-methylimidazole. The limits of detection are 0.5 ng mL(-1) and 0.5 ng g(-1), respectively. Fortified at 2, 10, 50, and 100 ng mL(-1) (ng g(-1)), inter-assay recoveries of EPR in cattle urine and feces were in the range of 87.9-91.5% and 78.6-86.3%, with coefficients of variation of 5.4-10.2% and 1.4-7.2%, respectively. Intra-assay mean recoveries of the analytes were 82.2-86.5% and 79.6-87.3%, with coefficients of variation of 7.8-11.5% and 6.3-7.8%, respectively. The method was used to study the excretion of eprinomectin in bovine urine and feces after subcutaneous administration at a dose of 0.5 mg kg(-1).