An Automated Immunoassay Based on Magnetic Microspheres for the Determination of Clenbuterol in Food

Abstract

An automated magnetic immunoassay for the determination of clenbuterol in food is reported. Magnetic microspheres were employed as the solid phase for binding anti-clenbuterol antibodies. Fe3O4 microspheres (506.9 nm) were synthesized from FeCl3 and ethylene glycol. The magnetic saturation value was 72.4 emu g−1 for the microspheres. The magnetic microspheres were subsequently surface modified using tetraethyl orthosilicate. Carboxylate groups were produced on the surface of the microspheres and the anti-clenbuterol antibodies were covalently attached using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide and N-hydroxysuccinimide. The incubation, washing, and detection procedures were automated. The limits of detection and quantification were 0.02 ng mL−1 and 0.1 ng mL−1, respectively. Recoveries of clenbuterol in sausage, pork, and beef were 93.5% to 110.0%, 98.9– 109%, and 94.0–101.9%, respectively. This approach allowed analysis in 25 min compared to 50 min for a commercial method while reducing the reagents required.