Speciation of thioarsenicals through application of coffee ring effect on gold nanofilm and surface-enhanced Raman spectroscopy
Speciation of thioarsenicals through application of coffee ring effect on gold nanofilm and surface-enhanced Raman spectroscopy
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DOI：
10.1016/j.aca.2020.01.042
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发表时间：
2020-04-15
影响因子：
6.2
通讯作者：
Cai, Yong
中科院分区：
文献类型：
--
作者：
Liamtsau, Valery;Fan, Changjun;Cai, Yong
硫代砷化合物，如二甲基一硫代砷酸（DMMTA（V））和二甲基二硫代砷酸（DMDTA（V）），已被越来越多地发现作为重要的砷代谢物，但这些不稳定的砷物种的分析仍然是一个具有挑战性的任务。基于表面增强拉曼光谱（Sers）检测结合咖啡环效应分离的方法，由于最少的样品预处理和独特的指纹拉曼识别，有望特别适用于硫代砷的分析。这种方法将提供一种替代方法，克服了基于高效液相色谱分离和质谱检测的传统砷形态分析技术的局限性。基于咖啡环效应和表面增强Sers的结合，建立了一种新的巯基砷化合物形态分析方法。金纳米膜（AuNF）不仅用作Sers基底，而且还用作分离硫代砷的平台。一旦将一滴硫代砷化物溶液置于AuNF上并且溶剂的蒸发和AuNF上的环印记形成开始，由于咖啡环效应的存在，Sers信号强度从蒸发的液滴的中心到边缘区域显著增加。通过计算DMMTA（V）和DMDTA（V）的pKa值并相应地操纵化学环境，实现了这些硫代砷化物的分离，因为它们在咖啡环的形成过程中行进了不同的距离。个别物种的迁移距离的影响，径向向外流动的溶质，硫代砷-金NF相互作用和热诱导的马兰戈尼流。咖啡环上的DMMTA（V）（中心）和DMDTA（V）（边缘）的分离，结合指纹Sers光谱，使得能够通过这种基于AuNF的咖啡环效应-SERS方法来识别这些硫代砷。(C)2020爱思唯尔B. V.保留所有权利。
Thioarsenicals, such as dimethylmonothioarsinic acid (DMMTA(V)) and dimethyldithioarsinic acid (DMDTA(V)), have been increasingly discovered as important arsenic metabolites, yet analysis of these unstable arsenic species remains a challenging task. A method based on surface-enhanced Raman spectroscopy (SERS) detection in combination with the coffee ringeffect for separation is expected to be particularly useful for analysis of thioarsenicals, thanks to minimal sample pretreatment and unique fingerprint Raman identification. Such a method would offer an alternative approach that overcomes limitations of conventional arsenic speciation techniques based on high performance liquid chromatography separation and mass spectrometry detection. A novel analytical method based on combination of the coffee ringeffect and SERS was developed for the speciation of thiolated arsenicals. A gold nanofilm (AuNF) was employed not only as a SERS substrate, but also as a platform for the separation of thioarsenicals. Once a drop of the thioarsenicals solution was placed onto the AuNF and evaporation of the solvent and the ring stamp formation onto AuNF began, the SERS signal intensity substantially increased from center to edge regions of the evaporated droplet due to the presence of the coffee ring effect. Through calculating the pKa's of DMMTA(V) and DMDTA(V) and accordingly manipulating the chemical environment, separation of these thioarsenicals was realized as they travelled different distances during the development of the coffee ring. The migration distances of individual species were influenced by a radial outward flow of a solute, the thioarsenicals-AuNF interactions and a thermally induced Marangoni flow. The separation of DMMTA(V) (center) and DMDTA(V) (edge) on the coffee ring, in combination with fingerprint SERS spectra, enables the identification of these thioarsenicals by this AuNF-based coffee ring effect-SERS method. (C) 2020 Elsevier B.V. All rights reserved.