Integration of Immunoassay with Conventional Methods in the Study of the Fate and Transport of Herbicides in Soil

Abstract

The persistence and mobility of herbicides in soil depend greatly on soil type, moisture, temperature, and microbial community. The mobility of herbicides can be measured in leaching experiments in the laboratory using soil columns, but studies of the movement of herbicides and their metabolites in soil under field conditions give direct information. In field dissipation studies, the soil is sampled in layers, and constituent concentration patterns are measured in a number of replicate samples. Consequently, in this type of study many samples need to be analyzed. In this situation enzyme-linked immunosorbent assay (ELISA) has proven to be a valuable analytical tool because it can cost effectively help determine herbicide concentrations in a large number of samples. In addition, because of the short analysis time of ELISA, unwanted further degradation of the herbicides in soil samples during storage can be avoided. Availability of timely information of the herbicide concentrations also may prevent unnecessary sampling.

This paper describes how immunoassay can be effectively used as both a screening and a quantitative tool in a field dissipation study of alachlor and metolachlor herbicides. A combination of ELISA, gas chromatography/mass spectrometry (GC/MS), high-performance liquid chromatography (HPLC), and solid-phase extraction (SPE) was effectively used for the analysis of soil, soil water, and runoff water from herbicide-treated fields. Using this combination of analytical methods, the relative mobility and persistence of both the parent herbicides and their ethanesulfonic acid (ESA) metabolites were cost effectively determined in experimental field plots located in Topeka, Kansas.

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Aga, D.S., Zimmerman, L.R., Yockel, M.E., and Thurman, E.M., 1996, Integration of immunoassay with conventional methods in the study of the fate and transport of herbicides in soil, in Preprints of Papers presented at the 211th ACS National Meeting in New Orleans, Louisiana, March 24-28, 1996: American Chemical Society, v. 36, no. 1, p. 88-89.

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