First carbonyl metallo immunoassay in the environmental area: application to the herbicide chlortoluron

We report a new, non‐isotopic, immunoassay (CMIA) for chlortoluron, a pesticide of the phenylurea family. The novel feature of this assay is the use of metal carbonyl complexes as tracers and Fourier‐transform infrared (FT‐IR) spectroscopy as the detection method. We describe the synthesis of three tracers, derivatives of chlortoluron with an attached cyclopentadienyl manganese tricarbonyl moiety. Quantitative analysis of these tracers, by FT‐IR spectroscopy was performed by simple measurement of the absorbance peak at 2033 cm^?1, characteristic of the ν_CO of the metal‐carbonyl unit. Immunoassays were carried out using the IgG fraction of rabbit antiserum. Standard curves obtained by CMIA for the three tracers showed the feasibility of this technique for chlortoluron assay. However, the IC₅₀ and IC₉₀ values obtained with the three tracers varied widely, with the long‐chain tracer 12 giving the most sensitive assay for chlortoluron, with an IC₅₀ value of 50 pmol (21 µg l^?1) and an IC₉₀ of 6.5 pmol (2.7 µg l^?1). Copyright © 2002 John Wiley & Sons, Ltd.