DETERMINATION OF CLENBUTEROL RESIDUES IN BOVINE LIVER, URINE, AND EYE BY ENZYME-IMMUNOASSAY

Simple enzyme immunoassays are described which enable clenbuterol to be determined in bovine liver homogenate and eye (aqueous humour and choroid/pigmented retinal epithelium) by direct analysis, and in urine following solid-phase extraction and concentration. The sensitivity, analytical recovery and linearity of response of the assays proved appropriate to the determination of clenbuterol in cattle seven days after cessation of a programme of treatment (0.8 mug clenbuterol per kg bodyweight, twice daily for four days). Concentrations determined in liver (range < 0.25 ng g-1 to 0.35 ng g-1) were approximately ten times higher than in urine (range 0.015-0.030 ng ml-1). Although clenbuterol could not be detected in aqueous humour, the choroid/pigmented retinal epithelium contained concentrations ranging between 12 and 14 ng g-1. These preliminary findings clearly indicate that choroid may be the tissue of choice to enable use or abuse of clenbuterol to be established following slaughter.