Electroanalysis Based on Disposable Gold Nanoparticle-plated Electrodes

• Main Authors: Yue-Shian Song, 宋岳憲
• Other Authors: Jyh-Myng Zen
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/46749949204079086077

博士 === 國立中興大學 === 化學系所 === 95 === In recent past, application of electrochemical methods for determination (sensors) in aquatic, industrial and biological has received a significant share of attention of world class scientist due to their simplicity, reduced cost and eco-friendly process. With the use of screen-printed carbon electrode (SPE) combined with suitable modifiers, heavy metals such as As3+, Hg etc., gases CO and O2 etc., are successfully identified in aqueous solutions electrochemically. This thesis has divided into three parts based on the nature of obtained results. The first part deals detection of As3+ using poly lactide gold nano-partilces modified screen printed electrode (PLA-AuNP/SPE). Preparation and characterization of PLA-AuNP/SPE was carried out using SEM, TEM and electrochemical technique. Competitiveness of PLA-AuNP/SPE on detection of As3+ was compared with other electrodes using differential pulse stripping voltammetry (DPSV). Wide range of linearity has been drawn on calibration plot (0.04-30 µM) with regression coefficient of 0.999 by maintaining the signal to noise ratio is 3 (S/N = 3). The sensitivity was good enough to detect As3+. This approach provided a selective detection for As3+ in aqueous solution and it helps to determine As3+ in natural water finally. The second part describes hydrogen sulfide detection by indirectly monitoring As3+ at a poly(L-lactide) stabilized gold nanoparticles modified SPE. Surface analysis by XPS together with electrochemical and Raman spectroscopic characterization were used to elucidate the detection mechanism. DPSV results showed a linear calibration curve in the window of 5-700 µM with the regression coefficient value and a detection limit (signal/noise = 3) 0.999 and 0.04 µM, respectively. The sensitivity observed in present study is good enough to detect sulfide at levels lower than the current EPA standard. The proposed electrochemical approach is successfully used for the determination of sulfide in acid rain and hot spring. The last part of this thesis demonstrates photocatalytic amperometric sensor for the determination of dissolved oxygen (DO) in phosphate buffer solution (PBS) using a disposable (AuNP/SPE). Experimental conditions for optimization of DPSV such as pH and potential were systematically worked out and found pH 8 PBS and -0.2 V vs Ag/AgCl, as optimum. The analytical applications for DO measurement showed a good linearity with appreciable regression coefficient comparable with that of recent DO reports. DPSV results obtained from real water samples using the proposed method also showed values close to the commercial DO meter. This method offers simple and easy DO measurements with good reproducibility. Finally consolidate the summery of the present work and points out the scope of the further work.