GAS AND LIQUID-CHROMATOGRAPHY COUPLED TO TANDEM MASS-SPECTROMETRY FORTHE MULTIRESIDUE ANALYSIS OF BETA-AGONISTS IN BIOLOGICAL MATRICES

beta-Agonists are substances used in veterinary and human medicine for the treatment of pulmonary disorders. They have found a use as growth promoters to improve meat-to-fat ratios in cattle but they are not au thorized for use in the European Union. Due to their presence in trace levels (usually less than 1 mu g/kg), to the diversity of the illegal ly used compounds and to the complexity of the biological matrices ana lysed, the detection of these residues requires a very sensitive and s pecific method of determination. This work describes the strategy of a nalysis we developed for five beta-agonists in urine and liver. The co mbination of improved solid- or liquid-phase extraction methods and LC or GC-MS-MS (in the multiple reaction monitoring mode) has shown to p rovide a system suitable for the control of these substances. The effi ciency of extraction and the sensitivity and selectivity allow this mu ltiresidue detection down to, and below, the UK regulatory level of 0. 5 mu g/kg. Moreover, the use of LC removes the need for the derivatisa tion step (cyclic methylboronate derivatives) which is required prior to GC-MS-MS analysis.