Voltammetric behavior of ofloxacin and its determination using a multi-walled carbon nanotubes-Nafion film coated electrode

A rapid, sensitive and simple electrochemical method is developed for the determination of trace-level ofloxacin, based on the excellent properties of multi walled carbon nanotubes (MWNT). The MWNT/Nafion film-coated glassy carbon electrode (GCE) is constructed and the electrochemical behavior of ofloxacin at the electrode is investigated in detail. Compared with the poor electrochemical signal at the unmodified GCE, the electrochemical response of ofloxacin at the MWNT/Nafion film-coated GCE is greatly improved. The determination conditions, such as the amount of MWNT-Nafion suspension, the pH values of the supporting electrolyte, accumulation potential and time, as well as scan rate are optimized. Under the chosen conditions, the concentration of ofloxacin shows excellent linear relationships with the oxidation peak current in the range of 0.5-100 mu mol L-1, with a low detection limit of 1 x 10(-7) mol L-1 (S/N = 3) for 20 sec accumulation at -1.2V. The proposed method has been successfully applied to determine ofloxacin in pharmaceuticals with excellent repeatability and higher sensitivity.