Polarographic determination of herbicide thifensulfuron methyl/application to agrochemical pesticide, soil, and fruit juice

Abstract

A novel, sensitive, simple, fast, and fully validated differential pulse polarographic (DPP) method for the determination of trace amounts of thifensulfuron-methyl in pesticide formulation, soil, and orange juice is reported. This procedure was based on a highly sensitive peak formed due to the reduction of thifensulfuron-methyl on a dropping mercury electrode over the pH range 1.00–10.00 in Britton–Robinson buffer. The polarographic reduction exhibits only a single peak in the pH ranges pH ≥ 3.0 and pH ≤ 6.0 and pH = 10.0 located at potential values of −1.010, −1.350, and −1.610 V (vs. SCE), respectively. The single peak appeared as a maximum at pH 3.0 (−1.010 V) was well resolved and suitable to be investigated for analytical use. This peak showed quantitative increments with the additions of standard thifensulfuron-methyl solution under the optimal conditions, and the cathodic peak current was linearity proportional to the thifensulfuron-methyl concentration in the range of 2 × 10−7–5 × 10−5 M. The limit of detection (LOD) and limit of quantification (LOQ) were obtained as 1.05 × 10−7 and 3.50 × 10−7 M, respectively, according to the relation k × SD/b (where k = 3 for LOD, k = 10 for LOQ, SD is the standard deviation of the blank, and b is the slope of the calibration curve). The proposed method was applied to pesticide formulation (Harmony® Extra), and the average percentage recovery was in agreement with that obtained by the spectrophotometric comparison method, 97.82 and 102.6%, respectively. The method was extended to determination of thifensulfuron-methy in spiked soil and orange juice, showing a good reproducibility and accuracy with a relative standard deviation of 4.55 and 1.40%, and relative errors of +2.80 and +1.90%, respectively.