去甲肾上腺素电化学行为的胶束效应

Electrochemical Oxidation of Norepinephrine in Micellar Systems

利用循环伏安法研究了不同pH值条件下去甲肾上腺素(NE)在玻碳电极上电化学氧化过程的胶束效应。结果表明,NE在玻碳电极上的氧化峰电位(Epa)和峰电流(Ipa)与表面活性剂的种类及浓度有关。Epa与Ipa值在表面活性剂的临界胶束浓度值(CMC)附近有一个突变,而在CMC以上时,Epa和Ipa值基本上不再随表面活性剂浓度的变化而改变。pH=6.8时,Epa值在水溶液中为364 mV,在CTAB胶束溶液中为420 mV,在SDS胶束溶液中为284 mV。表明SDS对NE的电化学氧化具有催化作用,而CTAB则阻化了NE的电化学氧化过程。

The electrochemistry of norepinephrine has been studied by cyclic voltammetry at a glass carbon electrode in the presence of cetyltrimethylammonium bromide （CTAB） and sodium dodecyl sulfate （SDS） micelles at different pH value. The anodic peak potential （Epa） and peak current （Ipa） are found to be remarkably dependent on the surfactant. The Epa, and Ipa change abruptly around the critical micellar concentration （CMC） of the surfactants and reach a plateau above the CMC. The Epa shifts to more positive value in the cationic CTAB micellar solution, e.g. from 364 mV（vs SCE）in aqueous solution at pH value of 6.8 to 420 mV in CTAB micelle, while it shifts to less positive value in the anionic SDS micellar solution, e.g. 284 mV at pH value of 6.8. It is concluded that SDS exhibits catalytic effect on the electrochemical oxidation of NE, while CTAB retards the oxidation.