DETERMINATION OF PHENYLBUTAZONE AND OXYPHENBUTAZONE IN BOVINE PLASMA USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH UV DETECTION

A simple and reliable method for the determination of phenylbutazone (PB) and its active metabolite oxyphenbutazone (OPB) in bovine plasma is described. After solvent extraction of plasma samples with acetonitrile and clean-up by solid phase extraction using C18 cartridges, analytes were determined by liquid chromatography with UV detection. Mean recovery values of PB and OPB from plasma samples fortified at the levels of 30–480 ng/ml were 52.0±7.0% and 69.0±7.8%, respectively. Repeatability, expressed as coefficient of variation, was below 15%. Limit of detection for PB was 18 ng/ml and for OPB - 12 ng/ml. Limit of quantitation of PB and OPB was 60 ng/ml each. Validation parameters and calculated performance criteria: decision limit (CCα) and detection capability (CCβ) indicate that the method is suitable for screening plasma samples for phenylbutazone and oxyphenbutazone.