Development of a broad-spectrum monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay for the multi-residue detection of avermectins in edible animal tissues and milk.

Avermectins (AVMs) are a group of anti-parasitic agents that have been widely used in food-producing animals. To monitor the residue of the AVMs, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed with a simple sample preparation procedure. Conjugates of 4″-HS-IVM/AVM on three different proteins were used to raise a broad-spectrum monoclonal antibody (mAb), 6D4, that had IC50 values for avermectin, ivermectin, eprinomectin and emamectin of 7.2, 10.4, 19.8 and 20.8 µg L-1, respectively. The limit of detection and limit of quantitation of this method for AVMs in various matrix samples ranged from 0.5 to 5.4 µg L-1 and 1.0 to 10.3 µg L-1, respectively. The recoveries of the samples spiked with AVMs were in the range of 78.1-110.5% with coefficients of variation below 14%. The ic-ELISA was applied to monitor ivermectin in the milk samples, and the results showed a good correlation with that of HPLC-MS/MS.