Preconcentration-enhanced electrochemical detection of paraoxon in food and environmental samples using reduced graphene oxide-modified disposable sensors†

Abstract

Organophosphates, such as paraoxon, are widely used as insecticides in agriculture, making their detection in environmental and food samples crucial due to their high toxicity. This study presents the development of an electrochemical sensor for the detection of paraoxon, using a screen-printed carbon electrode (SPCE) modified with electrochemically reduced graphene oxide (rGO). The modification enhanced the sensor's electrical conductivity and electrochemical performance. A novel preconcentration approach, involving potential pulses at −1.0 and 0.0 V, was employed to improve the adsorption of paraoxon on the electrode surface. Detection was performed by square wave voltammetry, and under optimized conditions, the rGO-SPCE sensor exhibited a linear range from 1.0 to 30 μmol L⁻¹, with detection and quantification limits of 0.26 and 0.86 μmol L⁻¹, respectively. The sensor demonstrated excellent repeatability (RSD = 4.22%), reproducibility (RSD = 7.14%), and selectivity (RSD < 9.22%). The method was successfully applied to tap water, grape and apple juices, and canned corn water samples, achieving recoveries of approximately 98% at the lowest concentration (1.0 μmol L⁻¹) with minimal matrix effects. This approach offers a simple, low-cost, and rapid method for paraoxon detection in water and food samples.