Evaluation of the carbonyl metallo immunoassay (CMIA) for the determination of traces of the herbicide atrazine

The non-isotopic immunoassay (CMIA) was investigated for the quantification of the herbicide atrazine. This assay combines transition metal carbonyl complex and Fourier transform infrared spectroscopy. We describe the synthesis of three dicobalt hexacarbonyl tracers, derivatives of atrazine. Their relative binding affinity towards two purified IgG fractions of polyclonal rabbit anti-sera (anti-atrazine and -simazine) was evaluated by ELISA and CMIA. The best tracer 9 (bearing the longest alkyl chain between atrazine aromatic ring and metal carbonyl complex) was used for further study by CMIA. Reproducible competitive standard curves were obtained by using anti-simazine antibodies in PBS buffer pH 7.4 with pre-incubation of various amounts of atrazine and antibodies for 1 h at 4 °C before addition of the tracer. This study demonstrates the feasability of using CMIA for pesticide determination, although the sensitivity of current CMIA format does not reach the 0.1 μg l−1 level required by E.U.