Trace level determination of cadmium and lead in coffee (Coffea) using gold nanoparticles modified graphene paste electrode
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Gold nanoparticles (AuNP) modified graphene paste electrodes (GPE) were fabricated using graphene powder, gold nanoparticles, and mineral oil. The fabricated electrodes were used as working electrode in anodic stripping voltammetry (ASV) for the determination of trace concentrations of cadmium (Cd2+) and lead (Pb2+). The modified GPE was characterized using scanning electron microscopy and cyclic voltammetry. Optimization of the electrode’s AuNP content and the ASV parameters was performed. It was determined that the GPE modified with 0.5 mg AuNP obtained the highest anodic current peaks for both Cd2+ and Pb2+. The calibration curves obtained using the said electrode showed a linear relationship between heavy metal concentration and peak current and the detection limits were found to be 256 ppb for lead and 267 ppb cadmium. The modified electrode was successful in determining traces of Cd2+ and Pb2+ in coffee samples. The presence of the heavy metals in the samples were verified using atomic absorption spectroscopy.