以差式脈衝伏安法偵測乙硫醇

Abstract

本研究中，我們以差式脈衝伏安法偵測乙硫醇，將catechol加入樣品溶液中做為電化學偵測上的媒介，在掃描過程中將catechol氧化成o-benzoquinone與乙硫醇反應形成catechol-thiol adduct，並偵測其氧化電流，透過此方法，使得偵測乙硫醇所需氧化電位降低約0.5V。使用差式脈衝伏安法對乙硫醇進行偵測，以反應後adduct的氧化電流對乙硫醇進行定量分析，此偵測方法線性範圍為0.65 uM - 59.3 uM (以丁醇為溶劑配製乙硫醇樣品)，其偵測極限為0.068 uM (S/N= 3)。在選擇性的偵測中，分別將甲硫醚、硫化氫、二氧化硫、苯乙烯、乙醛、二氧化氮加入於丁醇中做為干擾物測試，其中硫化氫的氧化電位與乙硫醇太過接近而會造成對乙硫醇偵測的干擾。在環境中乙硫醇氣體的偵測，以丁醇收集氣體樣品，當採集氣體為100L時，則測定範圍為0.4 - 37 (mg/m3)，此範圍符合環境保護署所制訂的標準。

We applied differential pulse voltammetry (DPV) to detect ethanethiol in this study. Catechol, added to the sample solution, was readily oxidized to form o-benzoquinone during the oxidation cycle. Ethanethiol then reacted with o-benzoquinone immediately to form a catechol-thiol adduct which was further oxidized during the same cycle. The oxidation potential of the adduct was found ~0.5 V lower than that of ethanethiol. Quantitative analysis was investigated using the DPV oxidation current. A linear dynamic range of 0.65 uM–59.3 uM (ethanethiol solution prepared in butanol) was obtained while the detection limit was 0.068 uM (S/N = 3). Interferences including dimethyl sulfide, hydrogen sulfide, sulfur dioxide, styrene, acetaldehyde, and nitrogen dioxide were doped in the butanol sample solutions in selectivity tests. Hydrogen sulfide created major problem due to its very close oxidation potential to ethanethiol. Detection of gaseous ethanethiol was also examined under the ambient environment. When gas volume of 100 L was collected in neat butanol, the detectable range of ethanethiol was found 0.4–37 mg/m3. This technique conformed to the regulation set by the Environmental Protection Agency.