POLAROGRAPHIC STUDY OF SIMAZINE IN MICELLAR AND EMULSIFIED MEDIA

A polarographic study of the reduction of the herbicide simazine in micellar solutions and oil-water emulsions is reported. The anionic surfactant sodium pentanesulphonate was chosen as the most suitable agent for micellar solutions and emulsions. In micellar solutions two reduction peaks were observed in differential-pulse polarography (DPP) below pH 2.0, whereas only one peak was obtained above pH 2.0. Ethyl acetate was chosen as the organic solvent to form simazine emulsions. Unlike in micellar solutions, DP polarograms of simazine in oil-water emulsions showed only one peak even at pH values lower than 2.0, suggesting that pesticide hydrolysis is hindered in the emulsified medium. The limiting current is diffusion-controlled and the electrode process is irreversible. The diffusion coefficient of simazine in emulsified medium was 8.85 x 10(-6) cm2 S-1, and the alphan(a) and K(f)-degrees values were 0.82 and 8.03 x 10(-14) cm S-1 respectively. Using DPP, simazine can be determined over the concentration ranges 8.0 x 10(-7)-4.0 X 10(-5) mol l-1. The limit of detection was 2.2 x 10(-7) Mol l-1. The effect of the presence of other herbicides belonging to the s-triazine family on the simazine reduction peak was studied. The method was applied to the determination of simazine in spiked irrigation water with good recoveries.