Electrochemical oxidation and voltammetric determination of the fungicide metalaxyl using a boron-doped diamond electrode

Abstract

This study investigates for the first time the electrochemical behavior and voltammetric determination of fungicide metalaxyl using boron-doped diamond electrodes. Cyclic voltammetry revealed an irreversible oxidation peak of metalaxyl at +1900 mV in 0.1 mol L−1 H2SO4. The oxidation process was found to be diffusion-controlled and independent of proton participation. Electrochemical conversion mechanism was elucidated by high performance liquid chromatography with high resolution mass spectrometry (HPLC-HRMS), identifying oxidation products. Differential pulse voltammetry (DPV) and square wave voltammetry (SWV) methods were optimized for metalaxyl determination, with DPV showing higher sensitivity and better peak resolution. Surface pre-treatment of BDDE by cycling enhanced signal repeatability and intensity. The developed DPV method exhibited a wide linear dynamic range (0.025–9.0 μmol L−1), low detection limit (0.0072 μmol L−1), and excellent measurement repeatability (RSD < 2.0 %). The method was successfully applied to analyze model solutions and spiked environmental water samples, demonstrating good recoveries also after pre-concentration using activated carbon or solid-phase extraction. This work presents a sensitive and reliable voltammetric approach for metalaxyl monitoring in environmental waters.