Reduced graphene oxide–CuO nanohybrid sensor for tipiracil hydrochloride: DFT assisted mechanistic insight, forced degradation profiling, and voltammetric determination in pharmaceutical formulations and biological fluids

The construction, characterization, and validation of novel disposable screen printed carbon electrodes (SPCEs) based on reduced graphene oxide‑copper oxide nanoparticles (rGO-CuONPs) nanohybrid was illustrated for sensitive differential pulse voltammetric quantification of tipiracil hydrochloride (TIP) in various pharmaceutical formulations and biological fluids. The modifier matrix was optimized on the basis of rGO/CuONPs ratio, where the surface morphology and the electroanalytical futures of the integrated electrode surface were fully characterized. Combination of rGO and CuONPs enhanced the sensor performance against the electrooxidation of TIP at 1.147 V following a diffusion controlled mechanism. Comprehensive theoretical molecular orbital calculations suggested oxidation of nitrogen atom (N5) within the TIP moiety and transfer of one proton/two electrons as sustained by the electroanalytical investigations. At the optimum measuring conditions, the constructed calibration curves were linear with the TIP concentration ranged from 0.015 to 2.238μgmL −1 , with LOD value 0.005μgmL −1 . The constructed rGO-CuONPs-SPCEs showed high measurement reproducibility, high mechanical stability with a prolonged shelf lifetime. The developed voltammetric approach has been reported to be suitable and reliable for routine analysis of TIP in the presence of impurities, related substances, and co-administrated drugs in pharmaceutical formulations and biological samples. • Fabrication and characterization of novel flexible rGO-CuONPs-SPCEs for differential pulse voltammetric determination of tipiracil hydrochloride (TIP). • Improved selectivity and sensitivity was recorded against TIP with, excipients, trifluridine, and degradation products. • Molecular orbital calculations sustained the proposed mechanism of TIP molecule.