Publication Abstract

Immunosensor for 2,4-Dichloro-phenoxyacetic Acid in Aqueous/Organic Solvent Soil Extracts

S. Kröger, S.J. Setford and A.P.F. Turner

The development of a simple electrochemical immunoassay procedure for the field-based quantification of the herbicide 2,4-D in methanolic soil extracts is presented. The sensor utilizes a competitive immunoassay format incorporating an immobilized antigen complex at the surface of a disposable screen-printed working electrode element. The extent of glucose oxidase-labeled antibody binding to the antigen-electrode is determined amperometrically and is related to sample analyte concentration. The performance of the sensor is assessed in bufer, 30% methanol, and methanolic soil extracts. The device is capable of quantifying 2,4-D in all three matrixes at the low ppm level with coefficient of variation values of 6.233.6%. The causes of the variation observed in the sensor response in different soil matrixes are examined and improvements proposed. The sensor, tested in parallel with a commercial 2,4-D immunoassay test kit, yields comparable quantitative data and detection limits while exhibiting greater assay simplicity.

Reference:

S. Kröger, S.J. Setford and A.P.F. Turner, 1998. Immunosensor for 2,4-Dichloro-phenoxyacetic Acid in Aqueous/Organic Solvent Soil Extracts. Analytical Chemistry, 70(23): 5047-5053.