利用含釕赤血鹽修飾玻璃碳電極偵測咖啡因

本研究目的是建立一個利用含釕赤血鹽(ruthenium hexacyanoferrate)來偵測咖啡因的系統。利用催化劑在pH 1環境中，將原本咖啡因的氧化電位約在1.54V下降至1.10V(vs.Ag/AgCl)。而催化劑的電位會受到環境pH值影響造成偏移，最低還可以下降至0.945V (vs.Ag/AgCl)。此系統經最佳化探討後，操作電位1.15V下，其偵測線性範圍從0.2μM至10μM，靈敏度為 298.05nA/μM，本系統偵測極限為 42.27nM (S/N=3)，對於1μM的咖啡因重複操作的相對標準偏差為2.86%(n=20)。最後利用HPLC將星巴克的美式咖啡分離出咖啡因，偵測器為本研究的催化電極， HPLC的分離條件為，流動相為75% 100mM pH 1 PBS和25%的70%乙腈混和，分離管柱為InertSustain AQ-C18 5um 4.6 x 250mm，流速為1ml/min，約7.7分鐘分離出來。

關鍵字

咖啡因；含釕赤血鹽；旋轉圓盤電極

並列摘要

The purpose of this study was to establish a system that uses catalysts of ruthenium hexacyanoferrate to detect caffeine. The oxidation potential of caffeine with ruthenium hexacyanoferrate was reduced to about 1.10 V at about 1.54V (vs. Ag/AgCl) in pH 1. And the potential of ruthenium hexacyanoferrate is affected by the environmental pH, which can be reduce to 0.945V (vs. Ag/AgCl). After optimization of this system, the operating potential is 1.15V, the linear range is 0.2μM to 10μM, the sensitivity is 298.05nA/μM, and the detection limit is 42.27nM (S/N=3). The relative standard deviation of the 1 μM caffeine repeat operation was 2.86% (n=20). Finally, the caffeine was separated in sample of caffé Americano(starbucks) by HPLC. And the detector use the system of this study. The caffeine was separated by a mobile phase of 75% 100 mM pH 1 PBS and 25% 70% acetonitrile, the column was InertSustain AQ-C18 5um 4.6 x 250m and flow rate was 1 ml/min by HPLC. And the caffeine was separated in 7.7 minutes.