Multi-residue liquid chromatography/tandem mass spectrometry method for the detection of non-steroidal anti-inflammatory drugs in bovine muscle: optimisation of ion trap parameters.

A multi-residue liquid chromatography/tandem mass spectrometry method (LC/MS2) was developed for the detection of the non-steroidal anti-inflammatory drugs acetylsalicylic acid (via the marker residue salicylic acid), flunixin, phenylbutazone, tolfenamic acid, meloxicam and ketoprofen, in bovine muscle. After extraction of the bovine muscle with acetonitrile, the cleanup was performed using a Oasis HLB column. The evaporated eluate was reconstituted and analysed by LC/MS2. To obtain optimal detection of salicylic acid and phenylbutazone, the ion trap mass spectrometric parameters activation q and maximum ion injection time, respectively, were optimised. The activation q for salicylic acid was increased to obtain reliable detection of both salicylic acid and its product ion. The maximum ion injection time for the time segment containing phenylbutazone was decreased since there were not enough scans across the chromatographic peak of this compound. The multi-residue method was able to detect the different analytes below or at the maximum residue limit (MRL) or minimum required performance limit (MRPL) or, in the case of phenylbutazone and ketoprofen, at 100 and 20 microg kg(-1), respectively.