Determination of phenylbutazone and oxyphenbutazone in animal urine by ion trap liquid chromatography–mass spectrometry Original Research Article

The purpose of this study was to develop and validate a method to determine oxyphenbutazone and phenylbutazone residues in urine of several animal species. Extraction from urine was performed using liquid extraction with chloroform after chemical hydrolysis. Final extract was analysed by reversed phase liquid chromatography–electrospray ionisation–mass spectrometry using an ion trap selective detector and phenylbutazone-D10 as internal standard. The method was validated according to the requirements of the 2002/657/EC European decision and the calculated decision limit (CCα) and detection capability (CCβ) were 2 and 3 ng ml−1, respectively.