Direct electrochemistry and voltammetric determination of midecamycin at a multi-walled carbon nanotube coated gold electrode

Macrolicle antibiotics generally shows slow electron-transfer rate and produces insensitive redox peaks at conventional electrodes. In this paper, we studied the electrochemical behavior of midecamycin, one of macrolide antibiotics, at a multi-walled carbon nanotube (MWNT) modified gold electrode. It was found that MWNT could adsorb midecamycin and promote its direct electron-transfer. Hence midecamycin exhibited a more sensitive anodic peak at the modified electrode. The electrochemical process showed the feature of a mixed-control system of diffusion and adsorption. Under the optimized conditions (i.e. pH 7.0 phosphate supporting electrolyte, 5 mu l 0.5 mg ml(-1) multi-walled carbon nanotube suspension for empty set = 2.0 mm electrode, accumulation at -0.8 V for 150s), the anodic peak current was linear to midecamycin concentration in the range of 5 x 10(-7) to 2 x 10(-5) M, with a correlation coefficient of 0.998. For a 5 x 10(-6) M midecamycin solution, ten repetitive measurements gave a relative standard deviation of 2.2%. This method was successfully applied to the determination of midecamycin in medicine tablet and the recovery was 97.5-104.0%. (C) 2011 Elsevier B.V. All rights reserved.