A simple, ultrasensitive and cost-effective electrochemical sensor for the determination of ciprofloxacin in various types of samples

In this study, a simple, ultrasensitive, inexpensive, and environmentally friendly sensor was developed for the electrochemical determination of ciprofloxacin (CPRO) using a choline chloride-modified carbon paste electrode (ChCl/CPE). The electrochemical properties of ChCl/CPE were examined by square wave voltammetry (SWV). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), ultraviolet-visible (UV–Vis) spectroscopy, and Fourier transform infrared (FT-IR) spectrometry were used for electrochemical and morphological characterizations. The sensor exhibits excellent conductivity and superior electrocatalytic activity, within the linear range of 0.005–200 μM, for the detection of CPRO in citrate buffer solution (CBS) at pH 5, with detection and quantification limits of 0.36 nM and 1.2 nM. The electroactive surface area of ChCl/CPE was calculated to be 0.123 cm3, which is four times higher than that of the bare CPE (0.037 cm2). The ChCl/CPE is not only simple, inexpensive and time-saving, but also has the lowest detection limit and widest linear range compared to the recently reported sensors for the determination of CPRO. The developed sensor also showed excellent reproducibility, repeatability, long-term stability, and exceptional selectivity against potentially interfering organic, inorganic, and antibiotic species. In addition, ChCl/CPE was successfully applied for the determination of ciprofloxacin in eye drops, river water, and egg samples with very good recoveries of 97–102% and relative standard deviations (RSD) of 0.27–3.85%. Therefore, the proposed electrochemical sensor is a potential candidate for the determination of ciprofloxacin in various matrices.