多巴胺和硫醇的電化學偵測

多巴胺(dopamine)是一種人體內重要的神經傳導物質，具有兒苯酚(catechol)的結構。之前研究發現多巴胺經由電化學氧化後，會形成o-dopaminoquinone (DOQ)，若溶液中同時含有親核試劑sodium sulfanilate (ABSA)，則DOQ會與親核試劑進行親核反應形成新的產物，使得多巴胺原本在Ered = 0.3 V vs. Ag/AgCl的還原訊號消失，在Ered = 0.1 V vs. Ag/AgCl生成一個新的還原訊號。本論文藉由偵測此產物並且以兩個未經修飾的工作電極結合流動注入分析法來對多巴胺進行定量。此偵測方法在多巴胺的濃度介於0.4 ~ 20 μM之間時，具有良好的線性關係。其偵測極限為0.048 μM。延續親核攻擊的特性，本論文還使用了p-phenylenediamine (PPD)作為指示劑，利用硫醇化合物與PPD的氧化物p-phenylenediimine (PDI)進行親核反應。藉由偵測反應後增強的氧化電流，對thiols進行定量的分析。

關鍵字

多巴胺；硫醇；親核性反應；流動注入分析法

並列摘要

Dopamine, the derivative of catechol, is an important neurotransmitter in human body. Dopamine can be oxidized to o-dopaminoquinone (DOQ) electrochemically. It was found that the nucleophilic attack of sodium sulfanilate (ABSA) to o-dopaminoquinone occurred and a new adduct was produced. The original reduction wave of dopamine at Ered = 0.3 V vs. Ag/AgCl is disappeared and a new reduction wave at Ered = 0.1 V vs. Ag/AgCl is appeared. The concentration of dopamine was determined in terms of the reduction current of the new adduct by using dual working electrode-FIA. The concentration of dopamine ranging from 0.4 to 20 μM gives a good linear relationship and the detection of limit is 0.048 μM. In the second part, the p-phenylenediamine (PPD) was used as an indicator for the determination of thiol. The oxidized form of PPD is PDI (p-phenylenediimine), which is attacked by thios nucleophiles. The increasing oxidation current after the addition of thiol into PDD solution was used to quantitative analysis of the concentration of thiols.