Carbonaceous Materials-12: a Novel Highly Sensitive Graphene Oxide-Based Carbon Electrode: Preparation, Characterization, and Heavy Metal Analysis in Food Samples

Abstract

Graphene oxide (GO) was covalently attached to glassy carbon (GC) electrode (GC–O–GO) for fabricating nanosensors to determine trace Pb²⁺ and Cd²⁺ using differential pulse anodic stripping voltammetry (DPASV). Surface characterization of the nanofilm-covered electrode was performed via electrochemical cyclic voltammetry (CV), transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) techniques. Surface pKa of the GO covalent attached GC (GC–O–GO) was calculated via CV. Under optimal conditions, a linear response was found for Pb²⁺ and Cd²⁺ in the range from 1 × 10⁻⁸ to 1 × 10⁻¹² M. The limit of detections (LODs) of Pb²⁺ and Cd²⁺ were 0.25 pM and 0.28 pM, respectively. The method shows good reproducibility, and stability was successfully applied to measure Pb²⁺ and Cd²⁺ levels in rice, soya, milk, and tap water samples, with good agreement with those obtained by the standard inductively coupled plasma optical emission spectrometry (ICP-OES) method. The method was evaluated by application with the simultaneous determination of the ions in food samples (n = 6) using the standard addition method. The recoveries of the Pb²⁺ and Cd²⁺ were up to 98 %.