Utilization of sodium montmorillonite clay-modified electrode for the determination of isoproturon and carbendazim in soil and water samples

Redox behavior of two pesticides namely isoproturon and carbendazim were investigated electrochemically using sodium montmorillonite clay-modified glassy carbon electrode in the presence and absence of a surfactant, cetyl trimethyl ammonium bromide. A solution of 0.1 M H2SO4 in both 50% aqueous alcohol (pH 1.0) was found to be a suitable medium for electroanalysis. Isoproturon exhibited one well-defined oxidation peak around 1.17 V along with one more oxidation and reduction peaks. Carbendazim showed only one well-defined anodic peak around 1.5 V The main electron transfer was irreversible and the mass transfer was by diffusion for both cases. Controlled potential coulometric studies revealed 2e(-) and 1e(-) transfer for isoproturon and carbendazim, respectively. The surfactant had only little effect on the electrochemical properties of isoproturon and pronounced effect with carbendazim. Electroanalytical procedure for the determination of these pesticides was developed using differential pulse stripping voltammogram under their maximum current experimental conditions. Calibration plot was made for both pesticides. The determination limit and standard deviations were arrived at. The applicability of the method was also verified in a soil sample and water analyte. (C) 2005 Elsevier B.V. All rights reserved.