Electroanalytical Determination of Antibacterial Ciprofloxacin in Pure Form and in Drug Formulations

A simple, rapid and sensitive electroanalytical method was developed to measure ciprofloxacin (CPF) concentration at an electrode surface made of a new composite material, electrochemically activated glassy carbon paste. Square-wave adsorptive stripping voltammetry comparisons of CPF measured at GCPE, glassy carbon and carbon paste electrode surfaces yielded the highest CPF signal at GCPE surfaces. When pH dependence was assessed, 0.1 M phosphate buffer solution, pH 5.0, showed the best anodic peak for CPF oxidation. When the conditions of the voltammetric method were optimized, a GCPE electrode surface 1.6 mm in diameter yielded a dynamic calibration curve (R (2) = 0.97) at CPF concentrations of 10-750 ppb. The limits of detection (3 sigma) and quantification were 12.2 ppb (33 nM) and 10 ppb (27 nM) CPF, respectively. The new composite electrode yielded reproducible results, with a relative standard deviation of 6.96 % (intraday) and 6.47 % (interday) for five repeated measurements of 0.5 ppm CPF. Finally, when this method was used to determine the concentration of CPF (active ingredient) in Floxacin tablets dissolved in pure buffer and in buffer containing 10 % fresh urine, the recoveries of CPF were 100 and 105 %, respectively. This method thus allows the direct determination of CPF in urine samples, making it suitable for routine analysis in clinical laboratories.