Voltammetric determination of ciprofloxacin in urine samples and its interaction with dsDNA on a cathodically pretreated boron-doped diamond electrode

Abstract

Voltammetric methods for the determination of the fluoroquinolone ciprofloxacin (CIP) were developed using a cathodically pretreated boron-doped diamond (BDD) electrode coupled with square-wave voltammetry (SWV) and differential pulse voltammetry (DPV). In cyclic voltammetric measurements, CIP electrooxidation was an irreversible process controlled by diffusion of the analyte to the electrode surface. Analytical curves were obtained for CIP concentrations from 2.50 to 50.0 μmol L⁻¹, for SWV, and from 0.500 to 60.0 μmol L⁻¹, for DPV, with detection limits of 2.46 and 0.440 μmol L⁻¹, respectively. On the other hand, adequate recovery values were obtained for the determination of CIP in synthetic urine samples by DPV. On the other hand, SWV was employed to evaluate the interaction between CIP and double-stranded dsDNA (calf thymus in aqueous solution). From the obtained results, we inferred that CIP binds to dsDNA by intercalation, with a binding constant calculated as 5.91 × 10⁵ L mol⁻¹. Thus, the cathodically pre-treated BDD electrode was successfully used for the determination of CIP in biological samples and for studies on the interaction of this fluoroquinolone with dsDNA.