Determination of eprinomectin in plasma by high-performance liquid chromatography with automated solid phase extraction and fluorescence detection

A method is described for the determination of eprinomectin in plasma using high-performance liquid chromatography with fluorescence detection (excitation and emission wavelengths 355 and 465 nm, respectively). The fluorescent derivative was obtained by a condensation reaction with trifluoroacetic anhydride and N-methylimidazole. The method employs 1 mi plasma samples and gives linear calibration graphs (r = 0.999) over the concentration range studied (0.5-50 ng ml(-1)). Solid extraction using the benchmate procedure was used for sample preparation. This method permits the determination of eprinomectin at levels as low as 0.1 ng ml-l and is suitable for the pharmacokinetic study of eprinomectin in animals.