Oxidation Behavior of Insecticide Azoxystrobin and its Voltammetric Determination Using Boron-doped Diamond Electrode

Abstract

Electrochemical oxidation of azoxystrobin, a systemic fungicide commonly used in agriculture to protect a wide variety of crops, was investigated using cyclic voltammetry with a boron-doped diamond electrode (BDDE) in aqueous buffer solutions. Two pH independent irreversible anodic current peaks controlled mostly by diffusion were observed in wide pH range (2 to 12) at potentials +1600mV and +2150mV vs. saturated silver-silver chloride electrode. Mechanism of the electrochemical oxidation was proposed and supported with high performance liquid chromatography/mass spectrometry analysis of azoxystrobin solutions electrolyzed on carbon fiber brush electrode. The main product of the first two-electron oxidation step was identified as methyl 2-(2-{[6-(2-cyanophenoxy)pyrimidin-4-yl]oxy}phenyl)-2-hydroxy-3-oxopropanoate. An analytical method for the determination of azoxystrobin in water samples and pesticide preparation by differential pulse voltammetry with BDDE was developed. The method provides a wide linear dynamic range (3.0x10(-7) to 2.0x10(-4)molL(-1)) with limit of detection 8x10(-8)molL(-1). Accuracy of the method was evaluated by the addition and recovery method with recoveries ranging from 96.0 to 105.8%. Interference study proved sufficient selectivity of the developed voltammetric method for the azoxystrobin determination in presence of azole fungicides as well as pesticides used to prevent the same crops.