A quantitative enzyme-linked immunoassay for the detection of 2, 6-dichlorobenzamide (BAM), a degradation product of the herbicide dichlobenil

2,6-Dichlorobenzamide (BAM) is the dominant degradation product in soil of the widely used herbicide dichlobenil. To detect BAM in water, a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) was developed. As an alternative to conventional coating of ELISA plates, the assay is based on direct covalent immobilisation.

We achieved a surface which requires a short time for the immobilisation of ligand, is stable under dry storage, and which permits assays with a low CV. The performance of the assay was demonstrated by an inter-well CV that was generally less than 6%, a detection limit (DL(15)) of 0.02 microg/l and an IC(50) of 0.19 microg/l.

Cross-reactivity was measured against nine analytes with structural homology to BAM. The highest degree of cross-reactivity (10.8%) was seen with 2,6-dichlorothiobenzamide (Chlorthiamid). Considering an EU-limit of 0.1 microg/l as the permissible maximum for the presence of pesticides in drinking water, this ELISA-procedure is suitable for large-scale screening of water samples suspected of being contaminated with BAM.