Abstract: An immunochip based on smart phone for simultaneous detection of four veterinary drugs including ractopamine (RAC), clenbuterol (CL), chloramphenicol (CAP), florfenicol (FF) and its metabolite florfenicol amine (FFA) in pig urine was developed in this study. The immunochip test was conducted based on the competitive reactions with the antibodies on nitrocellulose (NC) membrane. After chromogenic reaction, a calibration curve for the concentration of each veterinary drug versus the intensity of spots on the immunochip was established. The limits of detection (LODs) of the immunochip assay for RAC, CL, CAP, and FF were 0.146, 0.137, 0.035, and 3.73 ng/mL respectively, and the linear working ranges were 0.353–1.017, 0.309–0.897, 0.082–0.249, and 9.424–35.594 ng/mL, respectively. The cross-reactivity rate with FFA was 81.5%. The results determined by this method were consistent with those determined by colloidal gold immunochromatography assay (GICA) and enzyme-linked immunosorbent assay (ELISA). To sum up, this immune chip is a cheap, simple and powerful tool for on-site and high throughput screening of veterinary drug residues.

Key words: immunochip; veterinary drugs; simultaneous detection; smart phone