Mixed immunoassay design for multiple chemical residues detection.

In this research, a mixed immunoassay design for multiple chemical residues detection based on combined reverse competitive enzyme-linked immunosorbent assay (ELISA) procedure was developed. This method integrated two reverse ELISA reactions in one assay by labeling horseradish peroxidase to deoxynivalenol (DON) and orbifloxacin. Within this method, IC50 of the two mAbs for each analyte we produced ranged from 23~68 ng mL(-1) for DONs and 4.1~49 ng mL(-1) for quinolones (QNs). The limit of detection measured by IC10 was achieved at 0.45-1.3 ng mL(-1) for DONs and 0.59-6.9 ng mL(-1) for QNs, which was lower than the maximum residue levels. Recoveries in negative samples spiked at concentrations of 100, 200, and 500 ng mL(-1) ranged from 91.3 to 102.2 % for DONs and 88.7-98.05 % for QNs with relative standard deviation less than 9.88 and 12.67 %. The results demonstrated that this developed immunoassay was suitable for screening of low molecular weight contaminants.