Determination of heavy metals Cd (II) and Pb (II) with an electrochemically treated pencil graphite electrode in carbonated mineral water using anodic stripping voltammetry

Abstract

Abstract The starting point of this study was to propose a simple and rapid electrochemical approach for quantitative analysis of heavy metal ions in natural mineral water samples. For this purpose, it was aimed to quantitatively determine Cd (II) and Pb (II) ions in gaseous mineral waters by square wave anodic stripping voltammetry (SWASV) by modification of pencil graphite electrode (PGE) with graphene oxide (GO) and deposition of auric acid solution. A three-step modification process was implemented to the PGE surface, including graphene oxide coating (GO/PGE), GO reduction (ERGO/PGE), and gold coating (Au-ERGO/PGE). The morphologies and electrochemical properties of the developed electrode were checked with scanning electron microscopy (SEM), cyclic voltammetry (CV), and SWASV. The results show the synergistic effect of graphene oxide and auric acid-activated surface and good electrical conductivity leading to the deposition of Cd (II) and Pb (II) on the electrode surface. Under optimum conditions, a linear behavior was obtained between currents and Cd (II) and Pb (II) concentrations in the range of 0.6–1.6 µM and 0.4–1.6 µM. Detection limits were calculated as 0.36 µM and 0.24 µM for Cd (II) and Pb (II), respectively. Finally, the improved electrode was applied for the detection of Cd (II) and Pb (II) in gaseous natural mineral water samples with high recovery rates. This study revealed that Au-ERGO/PGE modification could be an alternative route in practical applications of electrochemical detection of heavy metal ions.