ELECTROCHEMICAL STUDY OF THE HERBICIDE TRIBENURON - DETERMINATION IN COMMERCIAL SAMPLES

The herbicide Tribenuron has been investigated. It has an acidic chara cter with a pKa value of 4.1. Hydrolysis was confirmed and its rate in creased with temperature and acidity, light influence was not observed . Electrochemical characteristics of this compound have been studied a t pH values from 1 to 7 by applying DC, TAST and DP polarography as we ll as cyclic and differential pulse voltammetry at the HMDE. The reduc tion of Tribenuron occurs in two processes, the first at pH < 7 and th e second at pH < 4. This study is devoted to the first process, which has been demonstrated to be irreversible and simultaneously governed b y diffusion and adsorption phenomena. Both hydrolysis and polarographi c reduction of Tribenuron yielded the same degradation products: 2-met hoxycarbonylbenzenesulfonamide and 2N-methyl-amino-4-methoxy-6-methyl- 1,3,5-triazine. The quantitative determination of Tribenuron can be ca rried out by DPP with a detection limit of 92 mu g/L or by adsorptive stripping voltammetry reaching a detection limit of 2.6 mu g/L. Assays of commercial samples are described.