Gold-based immunochromatographic strip for rapid ketoconazole detection

We developed a highly sensitive and specific monoclonal antibody (mAb) for ketoconazole (KCZ) detection in chicken samples. From indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) analysis, the 50% inhibitory concentration of the mAb was 0.7 ng/mL, and the cross-reactivity with fluconazole, imidazole, itraconazole, and voriconazole was <1%. Using indirect competitive enzyme-linked immunosorbent assay, spiked sample recovery was 92.5%-102.7%. Under optimal conditions, we also developed a colloidal gold immunochromatographic assay (CGIA) to detect KCZ residues in chicken samples, with a visual limit of detection of 0.5 ng/g and a cut-off value of 20 ng/g. When data were assessed using liquid chromatography with tandem mass spectrometry, no significant differences were found between assays. Also, strip results were revealed in 10 min. Therefore, our CGIA has great potential for rapidly detecting KCZ residues in chicken samples.