Electrochemically Inspired Copper(II) Complex on Disposable Graphite Pencil Electrode for Effective Simultaneous Detection of Hypoxanthine, Xanthine, and Uric Acid

A facile electrochemical method was developed by in-situ electrochemical complexation of Cu(II) ions with uric acid (UA), xanthine (XA) and hypoxanthine (HXA) on the disposable graphite pencil electrode (DGPE) surface for sensitive and selective simultaneous determination of UA, XA and HXA in phosphate buffer solution (PBS, pH 7.00±0.20). Raman Spectroscopy revealed the fluorescence nature of the corresponding Cu(II) – complexes of phosphate ions, UA, XA and HXA on DGPE while Density Function Theory (DFT) calculation was used to estimate their binding energies which are responsible for the enhanced peaks of UA, XA, and HXA as a result of their stronger interaction with copper atoms than phosphate ions. Square wave voltammetry was used in the analytical part. The calculated limits of detections were 14.42 nM, 5.04 nM and 4.93 nM for UA, XA and HXA, respectively. Potential interferences showed almost no significant effect on the peaks of UA, XA, and HXA, and the developed method was successfully utilized for simultaneous determination of the three analytes on human serum and urine with impressive percentage recovery.