Monoclonal antibody against sulfaquinoxaline and quantitative analysis in chicken tissues by competitive indirect ELISA and lateral flow immunoassay

A lateral flow immunoassay (LFIA) and a competitive indirect ELISA (ciELISA) were developed and validated for the quantitative analysis of sulfaquinoxaline (SQX) in chicken tissues. The limits of quantification of ciELISA were 5 ng/ml for muscle samples and 12.5 ng/ml for liver samples; recoveries in tissues spiked with SQX at 25, 40 and 50 ng/g were 73.4-87.4% (n = 5). With LFIA, no matrix effect was noticed during sample analyses. The optimisation of components allowed a detection limit of 0.5 ng/ml in tissues, which was 10-25 times lower than ciELISA. The recoveries in tissues fortified at levels 5, 10, 25 and 50 ng/g were 75.8-98% (n = 5). Using HPLC as confirmatory method, 70 chicken muscle and liver samples from animal experiments were analysed by two immunoassays. The assay time for LFIA was only five min, whereas the analyses by ciELISA and HPLC took several hours. Comparison of ELISA, LFIA and HPLC data showed good correlations (r(2)=0.99).