Sonovoltammetric determination of toxic compounds in vegetables and fruits using diamond electrodes

The direct determination of methylparathion in potato and corn extracts and its degradation product 4-nitrophenol in lemon and orange juices by ultrasound-assisted square wave voltammetry using diamond electrodes is reported here. The sonovoltammetric results for both analytes in pure water and in complex food samples showed greater sensitivity and precision and much lower limits of detection and quantification than the silent measurements. The limits of detection for methylparathion in water and corn extract were 4.86 and 10.1 μg L-1, respectively, values 55% and 72% lower than those obtained by silent voltammetry. The recovery values were also very satisfactory and varied between 83.5% and 96.2% for all systems. These improvements for the sonovoltammetric methods are due to electrode surface cleaning and mass transport enhancement towards the electrode surface and proved to be a powerful tool for the detection of toxic residues in complex samples without any pre-treatment or clean-up of the matrices.