Development and first application of the edge plane pyrolytic graphite electrode modified with graphene nanoplatelets for highly sensitive voltammetric determination of oxolinic acid

Abstract

In this paper, a graphene nanoplatelets (GNPs) were used as a modifier of an edge plane pyrolytic graphite electrode (EPPGE) surface, and the graphene nanoplatelets modified edge plane pyrolytic graphite electrode (GNPs–EPPGE) was prepared by simple drop casting procedure. The as-prepared GNPs–EPPGE was characterized by a cyclic voltammetry (CV), a scanning electron microscopy (SEM), and an atomic force microscopy (AFM). The electrochemical behavior of OxA on the EPPGE and the GNPs–EPPGE was performed using the cyclic voltammetry and an electrochemical impedance spectroscopy (EIS). Further, a sensitive and selective square–wave voltammetric (SWV) procedure using the GNPs–EPPGE was developed for the determination of a quinolone antibiotic oxolinic acid (OxA). An oxidation peak of OxA was observed in Britton–Robinson buffer solution with the highest response at pH 5.0 at potential c.a. +1.4 V vs. Ag/AgCl reference electrode. Compared to the unmodified EPPGE, the EPPGE modified GNPs exhibited a marked enhancement in the current response of OxA. Calibration curve on the GNPs–EPPGE was constructed in the concentration range of 3.0 × 10−7–9.1 × 10−6 mol L−1 with a correlation coefficient of 0.9997, a sensitivity of 1.39 μA L μmol−1, a limit of detection (LOD) of 5.2 × 10−8 mol L−1, and a limit of quantification (LOQ) of 1.7 × 10−7 mol L−1. The determination of OxA in the spiked human urine samples was carried out using the GNPs–EPPGE with the satisfactory recovery of 99.6%. The selectivity of the developed method for the determination of OxA using the GNPs–EPPGE was tested.