A Sensitive Sensor for Nano-Molar Detection of 5-Fluorouracil by Modifying a Paste Sensor with Graphene Quantum Dots and an Ionic Liquid

5-fluorouracil is a widely used anticancer drug with many side effects on humans, and hence its analysis in biological samples is very important. Accordingly, a novel sensitive electrochemical approach was fabricated by incorporating graphene quantum dots (GCD) and 1-butylpyridinium bromide (BPBr) in the formulation of a carbon paste electrode (GQD/BPBr/CPE). The GQD was synthesized and characterized TEM method and results confirmed them as being spherical with D~ of 5.0 nm. The applicability of the GQD/BPBr/CPE in voltammetric analysis of 5-fluorouracil was evaluated. The relations of oxidation currents and potentials of 5-fluorouracil with pH at the surface of GQD/BPBr/CPE were investigated and the results confirmed the involvement of electrons and protons in the electro-oxidation mechanism of 5-fluorouracil. In square wave voltammetry (SWV) analyses, the GQD/BPBr/CPE showed good sensitivity for 5-fluorouracil over a wide linear range of 0.001–400 μΜ and a detection limit of 0.5 nΜ was achieved. The GQD/BPBr/CPE was successfully applied for the determination of 5-fluorouracil in pharmaceutical samples and acceptable results were obtained.