DETECTION OF FLUNIXIN IN EQUINE URINE USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH PARTICLE-BEAM AND ATMOSPHERIC-PRESSURE IONIZATION MASS-SPECTROMETRY AFTER SOLID-PHASE EXTRACTION

A normal-phase HPLC method combined with particle-beam mass spectromet ry (PB-MS) was developed for the analysis of non-steroidal anti-inflam matory drugs (NSAIDs). The forty one NSAIDs analysed responded in one or more (electron impact, positive and negative chemical ionisation) m odes and highly characteristic spectra were produced. A mixed-mode sol id-phase extraction (SPE) method for isolating acidic NSAIDs was devel oped using the Bond Elut Certify II cartridge, The average recovery wa s 88.5%. Flunixin, extracted by SPE from urine of a mare to which the meglumine salt had been administered was positively identified by HPLC -PB-MS and HPLC-atmospheric pressure ionization (API) MS methods.