Exploring wood-derived biochar potential for electrochemical sensing of fungicides mancozeb and maneb in environmental water samples.

The sustainable material, biochar (BC) from a hardwood source, was synthesized via pyrolysis process at 400 °C (BC400) and 700 °C (BC700) and used as a modifier during the electrochemical sensor design. The prepared BCs were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and elemental analysis (CHNS). The development of rapid analytical techniques for detecting pesticides employing a low-cost carbon paste electrode (CPE) modified with BC is a novel strategy to provide a sensitive response to water pollution. The prepared working electrodes (unmodified CPE, BC400-CPE, and BC700-CPE) were compared for selected fungicides mancozeb (MCZ) and maneb (MAN) sensing, and BC700-CPE provides the most favorable analytical response of target analytes. Cyclic voltammetric investigations revealed that the electrode reaction is irreversible and controlled by the adsorption of MCZ and MAN at the surface of the BC700-CPE, which led to an optimization of the differential pulse adsorptive stripping voltammetric (DP-AdSV) method. The obtained working linear concentration ranges were 25-2780 μg L MCZ and 49-1840 μg L MAN in Britton-Robinson buffer pH 7.0 using CPE modified with 10 % BC700. The evaluated limit of detection was 7.5 μg L for MCZ and 15.0 μg L for MAN. Investigated interferences did not significantly affect the MCZ and MAN oxidation signal intensity. The developed DP-AdSV method was successfully applied to determine selected fungicides in spiked river water and wastewater samples, with good recovery and reproducibility.