SENSITIVE MULTIRESIDUE QUANTIFICATION OF PROCYMIDONE AND TEBUTHIURON ON CARBON PASTE ELECTRODE BY DIFFERENTIAL-PULSE VOLTAMMETRY

Abstract

Qualitative electrochemical characterization of procymidone (PRO) and tebuthiuron (TBH) was carried out by cyclic voltammetry using a carbon paste electrode. The studies suggest that analyte mass transfer is controlled by diffusion, and that oxidation of PRO and TBH occurs by means of irreversible electronic transfer of one electron. Oxidation of PRO and TBH occurs close to +0.820 V and +1.075 V (vs. Ag|AgCl, KCl 3.0 mol L^-1), respectively, in a 0.1-M KOH solution as supporting electrolyte. Quantitative analyses were carried out by differential-pulse voltammetry, a technique which is more sensitive and selective. Detection and quantification limits were determined for PRO and TBH in the absence of matrix, in a potable-water matrix, and in a nonpotable-water matrix, for which the ranges of reproducibility, intermediate precision and recovery rates were (1.01 and 4.20 %), (4.08 and 9.56 %), and (90.6 and 115 %) for PRO, and (1.59 and 3.92 %), (4.84 and 7.46 %), and (91.3 and 119 %), for TBH, respectively. The results indicate that the new method is selective, simple and cheap to simultaneously quantify PRO and TBH in water samples.