Abstract: This study established a competitive enzyme-linked immunosorbent assay (ELISA) method for detecting zilpaterol in animal derived food. Zilpaterol polyclonal antibody was obtained by immunizing New Zealand rabbit with zilpaterol-KLH conjugates. Checkerboard titration method was used to determine the optimum concentration of antibody and enzyme-labelled antigen. Coating condition, reaction time and the color developing time of substrate were also detected. The results showed that an ELISA kit with a linear sensitivity ranged from 0.15～10 ng/mL was successfully established. Half inhibitory concentration (IC₅₀) ranged between 0.43～0.79 ng/mL. The recovery rates for spiked zilpaterol in urine, feed, milk powder, milk and tissue were 65%～90% , with less than 15% coefficient variations (CV). The cross-reaction for other similar medicines was less than 0.1%. The ELISA kit established in current study for detecting zilpaterol in animal derived food and showed the good reproducibility, stability and specificity, hence it could be used to detect the zilpaterol residues in animal derived food.

Key words: animal derived food; enzyme-linked immunosorbent assay; zilpaterol