Electrochemical determination of lead ions in different samples using glassy carbon electrode modified with electroreduced graphene oxide and poly tryptophan in food samples

Lead ion (Pb²⁺) is one of the main metal pollutants in the environment and is among the most commonly used heavy metals in human life. Therefore, designing a simple and selective electrochemical sensor for detecting lead ions is important. In this study, for the first time, a glassy carbon electrode (GCE) modified with electroreduced graphene oxide (ErGO) and poly tryptophan (PTrp) was used to develop an electrochemical sensor for determination of lead ions via differential pulse anodic stripping voltammetry (DPASV). The modified electrode was characterized using fourier-transform infrared (FT-IR), and field-emission scanning electron microscopy (FE-SEM), and electrochemical techniques including electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). To improve sensor performance, several parameters such as pH, deposition time, and deposition potential were optimized. Under optimal conditions, a linear response from 0.0005 to 3500 nM with a detection limit of 0.00016 nM was obtained for Pb²⁺. The modified electrode exhibited favorable stability, reproducibility, selectivity, and repeatability. The PTrp/ErGO/GCE was successfully employed to detect lead ions in different food samples, with relative recoveries from 96 to 102% and RSD below 3.1%. For validation, atomic absorption spectrometry (AAS) was used as a reference method in actual samples.