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Timely, efficient on-site detection of pesticides such as methyl parathion (MP) is crucial to ensure public health. This study introduces the first disposable electrochemically reduced graphene oxide (ErGO) modified electrode for rapid MP detection. A square wave anodic stripping voltammetry method for the detection of MP was developed using these ErGO-modified carbon screen-printed electrodes. Based on this study, graphene's high electric conductivity and unique structure enhanced the sensitivity of the electrode for MP detection. Following optimization of the pH, equilibrium period, deposition potential, and period, the methodology demonstrated high sensitivity and reproducibility. Using the enhanced experiment conditions, calibration experiments were performed with a concentration range of 0 to 150 µg L-1 of MP. A consistent oxidation peak was observed at -0.180 V. The calibration data showed the increase in the peak height was linearly correlated to the increase in MP concentration, with a correlation coefficient of 0.9854. The sensitivity of the developed methodology was 0.0887 µA (µg L-1)-1, and the limit of detection was 9.06 µg L-1. The methodology was successfully applied to multiple water samples, specifically river water, groundwater, and General Test Water, with recovery rates of 106.01% (standard deviation = 1.46%), 109.51% (standard deviation=0.44%), and 97.69% (standard deviation=1.49%), respectively. [ABSTRACT FROM AUTHOR]

The present work reports a newly developed square wave anodic stripping voltammetry (SWASV) methodology using novel gold nanostar–modified screen-printed carbon electrodes (AuNS/SPCE) and modified Britton-Robinson buffer (mBRB) for simultaneous detection of trace cadmium(II), arsenic(III), and selenium(IV). During individual and simultaneous detection, Cd2+, As3+, and Se4+ exhibited well-separated SWASV peaks at approximately − 0.48, − 0.09, and 0.65 V, respectively (versus Ag/AgCl reference electrode), which enabled a highly selective detection of the three analytes. Electrochemical impedance spectrum tests showed a significant decrease in charge transfer resistance with the AuNS/SPCE (0.8 kΩ) compared with bare SPCE (2.4 kΩ). Cyclic voltammetry experiments showed a significant increase in electroactive surface area with electrode modification. The low charge transfer resistance and high electroactive surface area contributed to the high sensitivity for Cd2+ (0.0767 μA (0.225 μg L−1)−1), As3+ (0.2213 μA (μg L−1)−1), and Se4+ (μA (μg L−1)−1). The three analytes had linear stripping responses over the concentration range of 0 to 100 μg L−1, with the obtained LoD for Cd2+, As3+, and Se4+ of 1.6, 0.8, and 1.6 μg L−1, respectively. In comparison with individual detection, the simultaneous detection of As3+ and Se4+ showed peak height reductions of 40.8% and 42.7%, respectively. This result was associated with the possible formation of electrochemically inactive arsenic triselenide (As2Se3) during the preconcentration step. Surface water analysis resulted in average percent recoveries of 109% for Cd2+, 93% for As3+, and 92% for Se4+, indicating the proposed method is accurate and reliable for the simultaneous detection of Cd2+, As3+, and Se4+ in real water samples. [ABSTRACT FROM AUTHOR]