Electro-Oxidation and Determination of Ciprofloxacin at f-MWCNT@Poly-Aniline Glassy Carbon Electrode

A simple and sensitive electrochemical sensor was developed to quantify ciprofloxacin by restricted electro-polymerization of aniline on GCE followed by drop coating functionalized MWCNTs. Electro-catalytic activity of modified electrodes was investigated by EIS and CV revealed decrease in electrode’s charge transfer resistance and increase in electron transfer kinetics. Effect of pH and scan rate suggests a mixed adsorption-diffusion process. Tafel slope (plot of ln∣j _a ∣ or ln∣I _a ∣ against E) with linear relationship of potential vs logarithm of current on the linear sweep voltammogram determined the electron transfer coefficient (α). Using the value of (α), number of electrons (n) involved in the rate determining step was obtained. Surface coverage of analyte molecules adsorbed, and diffusion coefficient of ciprofloxacin were estimated from the Laviron and Randles Sevcik equations respectively. Peak current obtained by LSV for various concentrations of ciprofloxacin exhibited two linear ranges, 0.1 μM to 1 μM and 1 μM to 20 μM, with limit of detection 0.08 μM (RSD = 2.4%, S/N = 3). Presence of species existing abundantly in the sample matrix do not affect the sensor signal. Proposed ciprofloxacin sensor demonstrated high reproducibility, long-term stability and fast reaction. The fabricated sensor successfully determined ciprofloxacin in pharmaceutical formulations with recoveries between 92 to 104%.