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

• Published in: Electroanalysis (New York, N.Y.) Vol. 31; no. 2; pp. 363 - 373
• Main Authors: Šelešovská, Renáta, Herynková, Marie, Skopalová, Jana, Kelíšková‐Martinková, Pavlína, Janíková, Lenka, Cankař, Petr, Bednář, Petr, Chýlková, Jaromíra
• Format: Journal Article
• Language: English
• Published: 01.02.2019
• Subjects: Azoxystrobine; Boron-doped diamond electrode; Oxidation mechanism; Pesticides; Voltammetric determination
• ISSN: 1040-0397; 1521-4109
• DOI: 10.1002/elan.201800647

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 +1600 mV and +2150 mV 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 (3.0×10−7 to 2.0×10−4 mol L−1) with limit of detection 8×10−8 mol L−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.