Quercetin-rGO based mercury-free electrode for the determination of toxic Cd (II) and Pb (II) ions using DPASV technique

Metal ion pollution poses serious threat to environment. Analysis of Cd (II) and Pb (II) ions using chemically
modified mercury free electrode is a feasible routine analytical tool. Developing an electrode surface modified
with conductive 2D carbon and metal complexing ligand created a synergetic effect towards sensitive and se-
lective electrochemical determination of metal ions. The present study focused on green chemistry approach
towards synthesis of reduced graphene oxide using a natural flavonoid (Quercetin) that acts as a reducing, functionalizing agent and also as metal complexing agent. This quercetin reduced graphene oxide (Q-rGO) was
surface modified over paraffin wax impregnated graphite electrode. The resulting Q-rGO electrode was used as a
mercury-free electrode for simultaneous analysis of Pb (II) and Cd (II) ions. Physico-chemical parameters of the
synthesized Q-rGO and modified electrodes were characterized using X-ray diffraction, UV–Vis, FT-IR, and
Raman spectrometer. The morphology of the material and surface topography of the modified electrode was
observed using HR-TEM and FESEM, respectively. Cyclic voltammetry (CV) and AC impedance (EIS) were
adopted for electrochemical characterization and Differential pulse anodic stripping voltammetry (DPASV) was
chosen for simultaneous sensing of metal ions using Q-rGO electrode. Analytical parameters such as effect of

electrolyte, effect of pH, preconcentration time and deposition potential were optimized. The experimental re-
sults suggested that the Q-rGO electrode is capable of sensing Pb (II) and Cd (II) ions individually and simul-
taneously. Inference from the calibration plot showed that the Q-rGO electrode was capable of sensing the concentration range of Cd (II) ion form 0.19 to 2.5 μgL− 1 with LOD-0.05 μgL− 1 and Pb (II) ions from 0.19 to 3.1 μgL− 1 with LOD 0.06 μgL−