可拋棄式奈米白金碳墨修飾電極電化學偵測之研究

Abstract

奈米材料修飾電極具有擴大電極表面積，以增加接觸分析物的特性，可有效提升分析物的電子傳遞速度，並且改善其偵測靈敏度以及排除干擾物訊號等優點。傳統的工作電極具有靈敏度低以及選擇性不佳等缺點，因此近年來在電化學領域中有不少學者將奈米材料修飾在電極表面進而電催化分析物，改善這些傳統工作電極的缺點。本論文之研究主要以電化學分析技術，在三電極系統中的工作電極上進行奈米材料的修飾，並且藉由奈米材料修飾電極進行分析並且應用在真實樣品上。研究中使用循環伏安法電沉積的方式將奈米白金修飾在碳墨電極上，並且藉由掃描電子顯微鏡以及元素分析確認此修飾奈米白金方法的可行性。此修飾方法分別對兩種分析物進行偵測。第一，為分析污染水源中的砷離子，此部份所使用的偵測方法為安培法，安培法條件定電位於 + 0.9 V 偵測其砷離子的氧化電流，其線性範圍為0.5~250 □M，R2 = 0.9998，偵測極限為15.43 ng/mL。此修飾電極對於在水源中常見的氯離子干擾物，也可有效的排除其在偵測上所造成的干擾，將此修飾電極應用於三種水源的真實樣品上，其回收率均在93.2%以上 (RSD為7.8%以下)；第二為使用奈米白金修飾電極電催化三種雌激素，以安培法定電位於 + 0.6 V 做出三種雌激素的校正曲線，其中雌二醇之其線性範圍為0.05 ~ 11 □M，R2 = 0.991，偵測極限為2.1 nM，雌素酮所得到校正曲線其濃度線性範圍為0.05 ~ 9 □M，R2 = 0.993，偵測極限為4.9 nM (3σ/m，σ：STEVD，m：slope)，雌三酮作出來的校正曲線其濃度線性範圍為0.05 ~ 11 □M，R2 = 0.990，偵測極限為5.0 nM (3σ/m，σ：STEVD，m：slope)，對於干擾物氯離子具有排除干擾的效果，真實樣品雌二醇之回收率於103.7%以上 (RSD為9.6%以下)。因此本研究的奈米白金修飾電極對於偵測水中污染物：砷離子以及雌激素中對於人體影響較大的雌二醇有良好的準確度以及具有其應用的價值。

Recently, nanomaterials were wildly used in fabrication or modification of the traditional electrodes in electrochemical analysis. The sensitivity and selectivity of modified electrodes were large improved due to the high surface to volume ratio of nanomaterials. The working electrode in three electrodes system was modified with nanoplatinum particle on the surface of carbon ink electrode by single step cyclic voltammetry electrodeposition procedure and was applicated in analyzing of real samples. The surface of electrodes was characterized with scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) for its surface morphology and composition. In the first part of this study, arsenic (III) was measured with nanoplatinum modified carbon ink electrode by amperometry at fixed potential of +0.9 V for its oxidation current. The linear range of the calibration curve was 0.5~250 □M (R2 = 0.9998) and the detection limit was 15.43 ng/mL. The arsenic sensing was not interfered by chloride anion and other common interferences. The recoveries were higher than 93.2% in three water samples that spiking 10 μM of As with RSD of 7.8%. The second part in this study was using the same electrode to detect three estrogens using amperometry with fixed detecting potential at +0.6 V. The linear range of calibration curve for estradiol was 0.05~11 □M (R2 = 0.991) with limit of detection of 2.1 nM. The linear range of calibration curve for estrone was 0.05~9 □M (R2 = 0.993) with limit of detection of 4.9 nM. The linear range of calibration curve for estriol was 0.05~11 □M (R2 = 0.990) with limit of detection of 5.0 nM. The interferences of several cations and anions were not observed and the recoveries of three different water samples that spiking 50 nM of estradiol were 103.7% to 109.1% with RSD of 9.6%. The nanoplatinum modified carbon ink electrode was fabricated by single electrodeposition step in this study with high sensitivity, high reproducibility, high selectivity and low cost was suitable for detecting arsenic and estradiol in different real samples.