A Green Fieldable Analyzer for Arsenic

德克萨斯理工大学的Purnendu Dasgupta教授得到了分析和表面化学项目的支持，开发了一种新的环保工具，用于分析地下水样品和饮用水源中的各种砷物种。 大多数可现场使用的砷探测器涉及有毒化学物质铅和汞的使用。 此外，大多数检测试剂盒不适合分析低于10微克/升（世卫组织目前设定的可接受水平）的砷，本工作中开发的方法将提高这种灵敏度。 该仪器是基于顺序注射（形态），区域射流（氢化物发生）和气相化学发光（检测）。集成砷分析仪包括用离子交换柱浓缩和分离砷物种、电氧化As（III）为As（V）、用电解砷化氢发生器电还原As（V）为砷化氢、基于膜的电渗析盐分离器以及通过放电和氧气进料增强臭氧生成。它只需要使用氯化钠和电力，就可以分析亚微克/升水平的砷。通过初步设置，PI仅使用2 mL样品就达到了约0.1 ppb的检测限。通过调节酸度，他可以区分砷（III）和砷（V），并可以检测有机砷物种。这个项目包括了大学生，他们在一个学期的研究模块中工作。世界上数以百万计的威尔斯井可能含有高水平的砷。然而，这些威尔斯井中有许多还没有经过测试。除了急性毒性外，它还是一种已知的致癌物质，尤其是砷（III）。因此，监测地下水和饮用水处理设施中的砷物种非常重要。 这里正在开发的方法将适用于实地工作，甚至在印度和孟加拉国的农村地区遭受砷中毒的破坏。

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.