Identification of tylosin in bovine muscle at the maximum residue limit level by liquid chromatography-mass spectrometry, using a particle beam interface.

A particle beam liquid chromatography-mass spectrometric method is presented as a confirmatory technique for analysis of tylosin residues in bovine muscle. After chloroform extraction and a diol solid-phase extraction clean-up, on-line liquid chromatography-mass spectrometry (LC-MS) of extracts is carried out on an RP-18 bonded silica column. The analyte is introduced into the ion source by a particle beam interface and identified by negative chemical ionization with selective ion monitoring. The tylosin molecular ion is obtained with this ionization mode. The response of the ion chromatogram peak areas is linear for the three levels of spiked muscle analysed (0.5, 1 and 2 maximum residue limit). Under these LC-MS conditions, other macrolide antibiotics such as spiramycin and erythromycin do not interfere with tylosin.