Preparation of polyclonal antibody against dicamba and establishment of indirect competitive ELISA for dicamba detection

In order to establish the immunoassay method of dicamba(DIC), the diimine carbonization methods were used to synthesize immunogen and coating antigen by dicamba being conjugated to ovalbumin (OVA) and bovine serum albumin (BSA), respectively. The polyclonal antibodies against dicamba were prepared through immunizing New Zealand white rabbits with the immunogen. The enzyme-linked immunosorbent assay (ELISA) titer of the antibody was 1∶1.28×105. The percentages of the antibody cross reactivity with other analogues of dicamba (2, 3, 5-trichlorobenzoic acid, 2, 3, 6-trichlorobenzoic acid and 2-amino-3, 5-dichlorobenzoic acid) were all less than 0.1%. An indirect competitive ELISA (ciELISA) was developed for dicamba detection, with coating antigen and polyclonal antibody diluted at 1∶8 000 and 1∶80 000. The lineal range of the assay for detecting dicamba was 1 to 100 ng·mL-1, with the detection limit (IC20) of 1.779 ng·mL-1. The regression equation was y= 8.684 4 ln x+15.001, R2=0.994 4. When dicamba addition value was from 5 to 30 μg·kg-1 in the recovery tests, the recovery rate of dicamba in corn meal and wheat flour blank samples ranged from 53.08% to 92.37%, and 66.5% to 94.63%, respectively.