Huang Genin Gary, Yang Jyisy
Department of Chemistry, National Chung-Hsing University, Taichung, Taiwan 402.
Anal Chem. 2003 May 15;75(10):2262-9. doi: 10.1021/ac0264372.
A new infrared sensing scheme based on an evanescent wave was proposed in this work for selective detection of copper ion in aqueous solutions. This sensing scheme is based on the band-shifting technique to overcome the limitation that metal ions do not absorb IR radiation. To demonstrate that the proposed mechanism is feasible, both theoretical considerations and practical examination of copper ions in aqueous solutions were investigated. The IR sensor was constructed by surface modification with L-(-)proline to selectively interact with copper ions by formation of stable square-planar complexes. After complexation, the absorption bands of the immobilized L-(-)proline exhibits a band shift and could be used to monitor the quantity of metal ions in aqueous solutions. To immobilize L-(-)proline on the surface of a sensing element and increase the stability of the modified phase in aqueous solutions, poly(vinylbenzyl chloride) was coated onto the sensing element for further immobilization of L-(-)proline. A sensitive and a water-stable L-(-)proline phase was obtained. This sensing phase is selective and sensitive to copper ions due to the large formation constant between the copper ions and L-(-)proline. Factors, such as the copper ion concentration, response time, solution pH, long-term stability, regeneration efficiency, and the matrix effect, were investigated. Results indicated that the pH effect was significant but could be controlled by buffering the sample solutions. Using the optimal conditions found in this work, the detection limit could be lower than 0.7 microM and the linear regression coefficients in standard curves could be higher than 0.99 for a concentration range from 5 to 200 microM.
本文提出了一种基于倏逝波的新型红外传感方案，用于水溶液中铜离子的选择性检测。该传感方案基于带移技术，以克服金属离子不吸收红外辐射的限制。为了证明所提出的机制是可行的，对水溶液中铜离子进行了理论分析和实际检测。通过用L-(-)脯氨酸进行表面修饰构建红外传感器，使其通过形成稳定的平面正方形配合物与铜离子选择性相互作用。络合后，固定化L-(-)脯氨酸的吸收带出现带移，可用于监测水溶液中金属离子的含量。为了将L-(-)脯氨酸固定在传感元件表面并提高修饰相在水溶液中的稳定性，在传感元件上涂覆聚(乙烯基苄基氯)以进一步固定L-(-)脯氨酸。获得了一种灵敏且水稳定的L-(-)脯氨酸相。由于铜离子与L-(-)脯氨酸之间的形成常数较大，该传感相对铜离子具有选择性和敏感性。研究了铜离子浓度、响应时间、溶液pH值、长期稳定性、再生效率和基质效应等因素。结果表明，pH值的影响显著，但可通过缓冲样品溶液来控制。使用本研究中找到的最佳条件，检测限可低于0.7 microM，在5至200 microM的浓度范围内，标准曲线的线性回归系数可高于0.99。
