Detection of clenbuterol residues in bovine liver, muscle, retina and urine using gas chromatography/mass spectrometry.

A gas chromatographic/mass spectrometric method is described for the detection of clenbuterol residues in liver, muscle, urine and retina. Tissue samples are first digested using protease and any clenbuterol present is extracted using a simple liquid/liquid extraction procedure. The dried extracts are then derivatized using methylboronic acid and the derivates are subjected to gas chromatography/mass spectrometry on a magnetic sector instrument. The detection limit of the assay is 0.05 ng g-1 clenbuterol in liver, muscle or urine a 10 g sample size, and 4 ng g-1 in retina using a 0.5 g sample size. The assay is made very specific by using selected ion monitoring of three ions at a resolution of 3500 and by ion ratio measurements. The precision and reproducibility of the assay are enhanced by the use of a deuterated internal standard, with a typical coefficient of variation of 3%.