Determination of propazine by differential pulse polarography in micellar and emulsified media

Abstract

An electroanalytical study of the herbicide propazine's reduction process in micellar solutions and oil-in-water emulsions is reported. The anionic surfactant sodium pentanesulphonate was chosen as the most suitable. The differential pulse polarograms of micellar solutions had two reduction peaks below pH 2.0, whereas only one peak was obtained above pH 2.O. Ethyl acetate was chosen as the organic solvent to form propazine emulsions. Unlike in micellar solutions, the DPP polarograms of propazine emulsions showed only one peak even at pH < 2.0, suggesting that propazine hydrolysis was hindered in the emulsified medium. The limiting current is diffusion-controlled and the electrode process is irreversible. Propazine can be determined by differential pulse polarography over the 1.0 × 10⁻¹ − 1.0 × 10⁻¹moll⁻¹ and 1.0 × 10⁻¹5 − 4.0 × 10⁻¹ moll⁻¹ concentration ranges and the limit of detection was 2.8 × 10⁻¹ moll⁻¹. Of the potential interferents simazine, methoprotryne and terbutryn (alls-triazines), thiram (a dithiocarbamate), dinoseb (nitrophenolic), and heptachlor (chlorinated cyclo-diene herbicide), only the first two were significant (10% error for equimolar concentrations). The method was applied to the determination of propazine in spiked drinking water. At a concentration level of 2.0 × 10⁻¹ moll⁻¹ a recovery of 94 ± 6% was obtained, after tenfold concentration on Sep-Pak.