Zilpaterol—a new focus of concern in residue analysis Original Research Article

The results of an investigation on the residue behaviour of Zilpaterol in urine, plasma, muscle, liver, kidney and retina of cattle and pig are presented. Two heifers and 16 pigs were orally treated with ZILMAX™. The animals were slaughtered after withdrawal times varying from 1 to 10 days. The Zilpaterol concentrations in the samples were measured by means of LC–MS/MS. Zilpaterol was detectable at each point of time examined in all matrices but plasma after a withdrawal period of 10 days. A strong accumulation of Zilpaterol was observed in retinal tissue, where persistently high concentrations were measured.