Voltammetric behavior of urapidil and its determination at multi-wall carbon nanotube paste electrode.

The voltammetric behavior of urapidil was investigated. In pH 6.8 Britton-Robinson buffer, an irreversible oxidation peak of urapidil at 0.62V (versus SCE) at a multi-wall carbon nanotube paste electrode (MWNT-PE) was observed, which was more sensitive with lower potential than that at the carbon paste electrode (CPE). The oxidation of urapidil was a two-electron and two-proton process with adsorption character. A differential pulse voltammetric method was proposed for the determination of urapidil. The peak current of the oxidation peak of urapidil was linearly with its concentration in a range from 5.0x10(-8) to 2.0x10(-6)mol/L at open-circuit accumulation for 60s, with a detection limit of 3.8x10(-8)mol/L. The proposed method was employed to determine urapidil in urapidil tablets.