Quantum dot based multiplex fluorescence quenching immune chromatographic strips for the simultaneous determination of sulfonamide and fluoroquinolone residues in chicken samples

A novel multiplex fluorescence quenching immune chromatographic strip (FQICS), using quantum dots (QDs) as a fluorescence donor, was proposed to screen sulfonamide (SA) and fluoroquinolone (FQ) residues in chicken samples, simultaneously. The principle of the proposed FQICS is on the basis of the fluorescence quenching effect, and colloidal gold was used as the fluorescence quencher. The limit of detection (LOD) in standard solution was 3 ng mL(-1) and 0.6 ng mL(-1) for sulfaquinoxaline (SQX) and norfloxacin (NOR), respectively, through visual detection using UV. For specificity analysis, results obtained indicated that this established method could be applied in broad-spectrum detection of SAs and FQs. Then the proposed FQICS was successfully applied in semiquantitative analysis of SQX (30 mu g kg(-1)) and NOR (6 mu g kg(-1)) in spiked chicken samples. The results obtained using the strips showed great agreement with those obtained using an ELISA kit, which indicates the good accuracy of the strips. As a conclusion, the proposed FQICS with a signal "turn-on" mode provides a suitable immunoassay for rapid, sensitive and simultaneous screening of SAs and FQs in chicken samples on-site.