Electrochemical exfoliation of graphite from pencil lead to graphene sheets: a feasible and cost-effective strategy to improve ciprofloxacin sensing

In this study, we investigated the effects of electrochemical treatment based on cyclic voltammetry (100 cycles with a scan rate of 1 V s(-1)) on pencil graphite electrode (PGE), using different supporting electrolytes compositions (NaOH, HNO3, and KCl all in 0.1 mol L-1). Electrochemically treated electrodes (ePGE) were properly characterized by scanning electron microscopy, Raman spectroscopy, and X-Ray powder diffraction revealing that the proposed strategy provided an efficient exfoliation of graphene sheets on the electrode surface. Additionally, the ePGE showed a 43-fold increase in the electroanalytical response to ciprofloxacin (CIP) when compared to the untreated electrode. The sensor showed excellent analytical performance with a low detection limit (0.35 mu mol L-1), wide working linear range (from 5 to 100 mu mol L-1), and adequate precision (RSD <3.5%). In addition, the sensor provided adequate selectivity about other classes of antibiotics, and when applied to spiked samples, recovery values between 80 and 104% were obtained, which demonstrated satisfactory accuracy, as well as the absence of matrix effect. Thus, the electrochemical treatment provided a simple, fast, and affordable protocol to improve the electrochemical properties of PGE, making it a powerful tool for the investigation of other carbon-based substrates. [GRAPHICS] .

Automated summary

In this study, electrochemical treatment based on cyclic voltammetry was used to improve the properties of pencil graphite electrodes. The treated electrodes showed an efficient exfoliation of graphene sheets on the surface, leading to a significant increase in the electroanalytical response to ciprofloxacin. The sensor exhibited excellent analytical performance with a low detection limit, wide working linear range, and good selectivity and accuracy for antibiotic detection.