Effect of Surfactants on the Voltammetric Response and Determination of an Antihy pertensive Drug Phentolamine at Boron Doped Diamond Electrode

摘要

A boron doped diamond electrode (BDDE) was used for the electroanalysis of Phentolamine by cyclic voltammetry (CV) and square wave voltammetry (SWV) in BR buffer (pH2.5). The current signal due to the oxidation process was a function of the amount of Phentolamine, pH of the medium, surfactants and scan rate. The results were compared with a glassy carbon electrode at the same condition. Phentolamine undergoes irreversible reaction at both the electrodes. However BDDE showed highly reproducible results with increased current intensity. The higher electrocatalytic behavior of BDDE was analyzed by electrochemical impedance spectroscopy which showed a decrease in the charge transfer resistance. The potential sweep rate dependence of Phentolamine oxidation (peak currents linearly proportional to v~(1/2), with the range of 10 to 150mV S~(-1)) indicates that the oxidation current is diffusion controlled with the negligible adsorption on the BDDE surface. Moreover the effect of surface active agents on the voltammetric behavior of Phentolamine was also studied. Three surfactants were used, an anionic type, sodium dodecyl sulfate (SDS), a cationic type cetyl trimethyl ammonium bromide (CTAB) and a non ionic type, triton X-100. Addition of SDS was found to enhance the current signal whereas CTAB and triton X-100 showed no effects. The use of SDS in the electrochemical determination of Phentolamine using SWV enhanced the detection limit from 0.71μg/ml in the absence of surfactant to 1.07 μg/ml when present.