Dvoynenko Olga, Lo Shih-Lin, Chen Yi-Ju, Chen Guan Wei, Tsai Hsin-Mei, Wang Yuh-Lin, Wang Juen-Kai
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
Environmental Analytical Laboratory, Environmental Protection Administration, Taoyuan City 32024, Taiwan.
ACS Omega. 2021 Jan 8;6(3):2052-2059. doi: 10.1021/acsomega.0c05020. eCollection 2021 Jan 26.
Identifying and quantifying chromium in water are important for the protection of precious water resources from chromium pollution. Standard methods however are unable to easily distinguish toxic hexavalent chromium, Cr(VI), from innocuous trivalent chromium, Cr(III), are time-consuming, or require large sample quantity. We show in this report that Cr(VI) and Cr(III) in water can be differentiated based on their distinct spectral features of surface-enhanced Raman scattering (SERS). Their SERS signals exhibit different pH dependences: the SERS features of Cr(VI) and Cr(III) are most prominent at pH values of 10 and 5.5, respectively. The obtained limit of detection of Cr(VI) in water is below 0.1 mg/L. Both concentration curves of their SERS signals show Langmuir sorption isotherm behavior. A procedure was developed to quantify Cr(VI) concentration based on the direct retrieval or addition method with an error of 10%. Finally, the SERS detection of Cr(VI) is shown to be insensitive to co-present Cr(III). The developed SERS procedure offers potential to monitor toxic chromium in fields.
识别和量化水中的铬对于保护珍贵的水资源免受铬污染至关重要。然而，标准方法难以轻松区分有毒的六价铬（Cr(VI)）和无害的三价铬（Cr(III)），耗时较长，或者需要大量样品。我们在本报告中表明，水中的Cr(VI)和Cr(III)可以根据它们在表面增强拉曼散射（SERS）中的不同光谱特征来区分。它们的SERS信号表现出不同的pH依赖性：Cr(VI)和Cr(III)的SERS特征分别在pH值为10和5.5时最为突出。所获得的水中Cr(VI)的检测限低于0.1 mg/L。它们的SERS信号浓度曲线均呈现朗缪尔吸附等温线行为。开发了一种基于直接检索或添加法来量化Cr(VI)浓度的程序，误差为10%。最后，结果表明Cr(VI)的SERS检测对共存的Cr(III)不敏感。所开发的SERS程序为现场监测有毒铬提供了潜力。
