Electrochemical sensor development for detecting organophosphate pesticide using CuO nanograss electrode

Abstract In this work, copper oxide (CuO) nanograss (NGs) were synthesized on copper foil as electrodes through anodization and annealing processes. After the successful synthesis of the CuO NG electrode, it was characterized using field emission scanning electron microscopy (FESEM) and X‐ray diffraction (XRD) analysis. Anodization duration was optimized for NG synthesis and was found to be 20 min with the help of FESEM analysis. The synthesized electrodes were used to analyze the organophosphate pesticides (OPPs), namely ‘malathion’ and ‘chlorpyrifos’, in the absence and presence of interfering molecules using differential pulse voltammetry (DPV). The proposed sensor functions based on the current inhibition ratio. The parameters like pH, accumulation time, and ionic strength of supporting electrolyte were optimized to be 7 pH, 9 min, and 0.1 M potassium chloride (KCl), respectively, for determining the current inhibition ratio (ΔI/I 0 ). The developed sensor was sensitive and selective, with limit of detection (LOD) as low as 1 ppb for both pesticides. The limit of quantification (LOQ) was 1 ppb for chlorpyrifos and 10 ppb for malathion. The sensor's selectivity was also studied by adding Pb(NO 3 ) 2 , Zn(NO 3 ) 2 , NiCl 2 , and carbendazim to a fixed malathion and chlorpyrifos concentration, and minimal interferences were observed in the detection of malathion and chlorpyrifos. The sensor's functionality was validated using an unknown concentration of malathion and chlorpyrifos in water and food samples with an average recovery of 95% when analyzed with the electrochemical method and high performance liquid chromatography (HPLC). The sensitivity of the electrochemical sensor for chlorpyrifos detection was found to be 0.6678 μA/ppb, and for malathion detection, it was found to be 1.139 μA/ppb.