Fabrication of a Multi-wall Carbon Nanotubes Modified Glassy Carbon Electrode and its Catalytic Effect on the Oxidation of Estradiol, Estrone and Estriol

 Multi-wall carbon nanotubes (MWNT) have been dispersed into water with the emulsification of oil of turpentine and emulsifier OP TX-100. An MWNT-modified glassy carbon electrode (GCE) has been achieved through solvent evaporation of MWNT- dispersion. In pH 2.0 phosphate buffer, MWNT- modified GCE has an obvious catalytic effect on the oxidation of estradiol, estrone and estriol. The oxidation peak current of these estrogens at the modified electrode increases significantly in contrast with that at the bare GCE. The experimental conditions which heavily affect the oxidation peak current of estradiol, such as the solution pH, the amount of MWNT, the scan rate, the adsorption potential and adsorption time, were optimized. The peak current is linear to the concentration in the range of 2.5 × 10⁻⁷ to 5 × 10⁻⁵ mol L⁻¹ estradiol. The detection limit is 1 × 10⁻⁸ mol L⁻¹ after 3 min open-circuit adsorption. The relative standard deviation (RSD) of six measurements using an electrode is 3.2% for 1 × 10⁻⁵ mol L⁻¹ estradiol. The effect of interferences of other organic compounds on the determination of estradiol was examined. Author for correspondence: Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China. E-mail: sshu@whu.edu.cn Received June 19, 2002; accepted January 4, 2003 Published online April 11, 2003