The Interactions of Four Carbamate Pesticides with Electron-acceptor Reagents

Abstract

The interactions between several electron-acceptor reagents and some pesticides having donor properties were investigated in solution and on cellulose thin-layers by spectrophotometric methods. In solution, formation constants and extinction coefficients were evaluated from absorbance measurements for complexes of the pesticides carbaryl, IPC, CIPC, and swep with the electron-acceptor reagent 9-dicyanomethylene-2,4,7-trinitrofluorene using the Benesi-Hildebrand method. Values were also calculated for the carbaryl-mellitic trianhydride complex. Extinction coefficients for the complexes were less than 1000, while formation constants were 1-4 1 mol-'.Reflectance spectroscopic measurements showed similar relationships between absorption maxima and intensities of the complexes and the donor properties of the pesticides to those observed in solution. A linear relationship between reflectance and the square root of concentration was found for all four pesticide-CNTNF complexes in the range from 5-50 pg.