Fabrication and Analytical Investigation of Reduced Graphene Oxide and Poly-L-Glutathione Based Voltammetric Sensor for the Individual and Simultaneous Determination of Purine Derivative and Metabolites

Abstract

Purine metabolites are considered as recognized disease biomarkers and food quality inspecting parameters. Hence, reliable electro-analytical strategies for the quantification of purine bases are indispensable in clinical point of view. This article proposes an efficient voltammetric sensor based on reduced graphene oxide and poly-L-Glutathione modified glassy carbon electrode (GCE) for the determination of purine bases such as Uric acid (UA), Xanthine (XA), Hypoxanthine (HX) and Theobromine (TB). Surface characterisation of GCE has been carried out via surface area determination, Scanning Electron Microscopy, Atomic Force Microscopy, Raman spectroscopy, Attenuated Total Reflection Spectroscopy, Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. For the simultaneous determination, the sensor offers a limit of detection of 1.83 × 10−7 mol l−1, 6.70 × 10−8 mol l−1, 2.12 × 10−7 mol l−1 and 1.14 × 10−6 mol l−1 for UA, XA, HX and TB respectively. The practical utility of the sensor has been ascertained via analysis in real samples and the findings are validated using conventional analytical methods. Mechanistic aspects involved in the electrooxidation of analytes have been derived using scan rate studies. Wide concentration linear range with low limit of detection and successful applicability studies in tea, coffee, cocoa and artificial physiological samples point towards the efficacy of the analytical assay in real sample analysis.