Detection of sulphathiazole in honey samples using a lateral flow immunoassay.

A lateral flow immunoassay (LFIA) was developed in the competitive reaction format and applied to test sulphathiazole (STZ) residues in honey samples. To prepare the assay test, a hapten conjugate and goat antirabbit antiserum as capture and control reagent, respectively, were dispensed on nitrocellulose membrane. Polyclonal antiserum against sulphathiazole was conjugated to colloidal gold nanoparticles and used as the detection reagent. The visual limit of detection (cut-off value) of the sulphathiazole LFIA was 15ng/g, reaching qualitative results within 10min. The assay was evaluated with STZ spiked honey samples from different geographical origins (n=25). The results were in good agreement with those obtained from liquid chromatography separation and mass spectroscopy detection (LC-MS), indicating that the LFIA test might be used as a qualitative method for the determination of sulphathiazole residues without expensive equipment. The test was also highly specific, showing no cross-reactivity to other chemically similar antibiotics. To our knowledge, this is the only work where a development of LFIA tests for the detection of sulphathiazole residues is performed.