Abstract: A method for the determination of five β₂-agonists in pig feed, liver, meat, and urine samples by micellar electrokinetic chromatography was developed. The separation and detection conditions were optimized in terms of SDS concentration, running buffer pH and concentration, capillary temperature. Under the optimized conditions (15 mmol/L borate, pH=10, 15 mmol/L SDS, and 25 ℃), all five analytes in the spiking samples were separated and identified within 18 min. Good linearity (R²>0.999) was obtained for the analytes in the range of 0.1-40 μg/mL with the limit of detection (S/N ≥ 3) in the range of 0.05-0.08 μg/mL. The satisfactory recoveries of cimaterol, ractopamine and clenbuterol were obtained in the range of 93.1%-95.8%, whereas the recoveries of salbutamol and terbutaline were at 52.3% and 69.4%, respectively. The relative standard deviations of peak area and migration time of the analytes were less than 4.86% and 1.25%, respectively. The method was successfully applied to monitor the presence of the selected β₂-agonists in pig feed, liver, meat and urine samples.

Key words: β₂-agonist, micellar electrokinetic chromatography, screening