A Green Fieldable Analyzer for Arsenic

德克萨斯理工大学的Purnendu Dasgupta教授在分析和表面化学计划的支持下，开发了一种新的环境友好型工具，用于分析地下水样本和饮用水水源中的各种砷形态。大多数现场砷探测器涉及有毒化学物质铅和汞的使用。此外，大多数试剂盒不适合分析低于10微克/L(世卫组织目前可接受的水平)的砷，而这项工作中开发的方法将提高这种灵敏度。该仪器基于顺序进样(用于物种形成)、区域流体(用于氢化物生成)和气相化学发光(用于检测)。集成的砷分析仪包括用离子交换柱浓缩和分离砷形态，As(III)电氧化成As(V)，用电解砷发生器将As(V)电还原成砷，膜基电渗析盐分离器，以及通过放电和供氧增强臭氧产生。它只需要使用氯化钠和电力就可以在亚微克/L水平上进行砷的分析。在初步设置的情况下，PI仅使用2毫升样品就达到了约0.1 ppb的检测下限。通过调节酸度，他可以区分砷(III)和砷(V)，并可以检测出有机砷的种类。该项目包括在长达一学期的研究模块上工作的本科生。世界各地的数百万口井可能含有高水平的砷。然而，这些油井中有许多还没有经过测试。除了它的急性毒性外，它还是一种已知的致癌物质，特别是砷(III)。因此，重要的是监测地下水和饮用水处理设施中的砷形态。这里正在开发的方法将适用于野外工作，即使在印度和孟加拉国被砷中毒摧毁的农村地区也是如此。

Professor Purnendu Dasgupta of Texas Tech University is supported by the Analytical and Surface Chemistry program to develop a new environmentally friendly tool for the analysis of various arsenic species in groundwater samples and drinking water sources. Most fieldable arsenic detectors involve the use of the toxic chemicals lead and mercury. Further, most test kits are not suitable for analyzing arsenic below 10 microgram/L (the current acceptable level set by WHO), and the method developed in this work will improve this sensitivity. The instrument is based on sequential injection (for speciation), zone fluidics (for hydride generation), and gas phase chemiluminescence (for detection). The integrated arsenic analyzer includes concentration and separation of arsenic species with ion exchange cartridges, electrooxidation of As(III) to As(V), electroreduction of As(V) to arsine with an electrolytic arsine generator, membrane-based electrodialytic salt splitter, and enhanced ozone generation by electrical discharge and oxygen feed. It only requires the use of NaCl and electricity to enable analysis of arsenic at the sub-microgram/L levels. With a preliminary setup, the PI achieved detection limits of around 0.1 ppb using only a 2 mL sample. By adjusting acidity, he can distinguish between arsenic(III) and arsenic(V), and he can detect organic arsenic species. The project includes undergraduates who work on semester-long research modules.Millions of wells around the world may contain high levels of arsenic. However, many of these wells have not been tested. Besides its acute toxicity, it is a known carcinogen, especially arsenic(III). Hence, it is important to monitor the arsenic species, both in groundwater and drinking water treatment facilities. The method being developed here would be applicable to field work, even in rural areas of India and Bangladesh devastated by arsenic poisoning.