Determination of Cymoxanil Fungicide in Commercial Formulation and Natural Water by Square-wave Stripping Voltammetry
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Voltammetric behavior of cymoxanil fungicide dissolved in water-acetonitrile (1:1) solution was investigated by square-wave stripping voltammetry (SWSV) and cyclic voltammetry (CV). The cymoxanil was accumulated at -400 mV on a hanging mercury drop electrode (HMDE) and a well-defined cathodic peak obtained at -680 mV (pH 7.0). The optimal experimental parameters for the cymoxanil assay were an accumulation potential of -400 mV (vs. Ag/AgCl/KCl), accumulation time 10 s, frequency 350 Hz, and pulse amplitude 75 mV. The cyclic voltammetric measurements showed an irreversible nature of the reduction wave at HMDE in the range of scan rates comprised between 5 and 4000 mV/s. The calibration curve obtained from SWSV was linear in the range 23.6-1950 mu g/L with a detection limit of 7.1 mu g/L. The method was applied to the direct determination of fungicide in water samples. Recoveries calculated for river and tap water samples spiked with 40 mu g/L level were 40.2 +/- 0.8 and 39.8 +/- 0.9 mu g/L at 95% confidence level, respectively. The method was extended to determination of cymoxanil in agrochemical formulation Tri-Miltox Max (R) with recovery of 102.5%. The sufficiently good recoveries and low relative standard deviations reflect the high accuracy and precision of the proposed square-wave voltammetric method. Influences of some interfering species were also investigated.