DETERMINATION OF ORGANOCHLORINE PESTICIDES BY POLAROGRAPHY IN EMULSIFIED MEDIUM

A polarographic study of the organochlorine pesticides dieldrin, heptachlor, endosulfan, and endosulfan sulfate in an emulsified medium formed with ethyl acetate and a mixture of two surfactants, Hyamine 2389 and Triton X-405, as emulsifying agent, is reported. Well-defined peaks were obtained by differential pulse polarography (dpp). Neither preceding acid-base equilibria nor mechanism changes are involved in the reduction processes. The characteristics of the electrode processes were examined at pH 8.0 for heptachlor and at pH 6.0 for the other pesticides. The diffusion coefficients were calculated as well as the kinetic parameters alpha-n(a) and k(f,h)0. The mechanisms of the polarographic reduction processes are proposed and the different behavior of heptachlor is discussed. Linear calibration plots were obtained using dpp over different concentration ranges: the analytical characteristics of the methods were determined. The effect of the presence of the other pesticides on the i(p) and E(p) values of each one of the four pesticides was studied. Simultaneous determination of heptachlor and endosulfan sulfate was possible.