Electrochemical Behavior of the Antibiotic Minocycline and its Voltammetric Determination in Pharmaceutical Formulations at Carbon Paste Electrode

An analytical method for the determination of the drug minocycline in pharmaceutical formulations using differential pulse voltammetry was developed. Voltammetric analysis of minocycline using a carbon paste electrode revealed a well-defined peak at 0.40 V (vs. Ag/AgCl), corresponding to the oxidation of minocycline at pH 4.0. The electrodic behavior indicated that the oxidation process was reversible, and that it was controlled by diffusion. After the optimization of the experimental conditions, calibration curves were obtained in the linear concentration range from 1.0 x 10(-6) to 2.3 x 10(-5) mol L-1 resulting in a detection limit of 7.0 x 10(-7) mol L-1 and the quantification limit of 2.2 x 10(-6) mol L-1. In addition to advantages such as high selectivity and sensitivity, the method developed could be used for the analysis of pharmaceutical formulations containing minocycline without any need for prior sample treatment, an important consideration in routine analysis laboratories.