等离子体（电）化学蒸气发生方法研究

Chemical Vapor generation (CVG) is commonly used for elements determination due to its high sample introduction efficiency and capability to separate the analytes from matrix. However, the borohydride (NaBH4) used in conventional CVG is expensive and its aqueous solution is unstable, and the general reaction conditions are not compatible with green chemistry strategies. In this project, novel vapor generation methods are proposed based on plasma （electro-）chemical process：1）In DBD plasma-CVG，dissolved metal ions are readily converted to volatile species by reaction with hydrogen, which eliminates the use of unstable reducing agents and reduces the interference from transition metal ions; 2) In plasma-electrochemical VG, the metal cathode is replaced by liquid discharge plasma compared with conventional electrochemical hydride generation (EcHG). Thus, careful selection of the cathode material and frequent cleaning of the electrode is avoided. The present project will focus on the investigation of vapor generation behavior of different elements in plasma chemical reactor. The characteristic of the plasma and matrix effects on vapor generation will be evaluated in detail. The impact of the form of element on the vapor generation will also be investigated. In addition, we will try to improve the performance of plama-CVG by evaluating the effect of different catalyst. After that, the method will be applied to development of new methods for element speciation. Finally, the proposed method will be extended to isotope analsysis through hyphenation with MC-ICP-MS. The proposed plasma-CVG provides an alternative way for trace-elemental analysis and may also be promising for the development of new methods for elemental speciation and isotope analysis.

样品引入技术是限制原子光谱分析性能的瓶颈问题，蒸气发生方法由于具有可以显著提高样品引入效率、分离基体等优点，一直是光谱分析研究的热点问题。然而，常规的化学蒸气发生以及电化学蒸气发生等都具有明显的不足。本项目我们提出了基于等离子体（电）化学的新原理的蒸气发生方法，通过介质阻挡放电及液体放电等离子体（电）化学过程将金属离子高效的转化为挥发性蒸气。方法避免了不稳定化学试剂的使用，等离子体电化学氢化物发生更是解决了常规电化学发生过程中阴极材料影响的问题，具有抗干扰强、阴极无需处理、使用寿命长等优点。项目重点研究等离子体条件对不同元素蒸气发生的影响；考察催化剂与等离子体协同作用下的元素蒸气发生行为；研究元素形态对蒸气发生的影响，将此蒸气发生技术应用于元素的形态分析。最后，利用该蒸气发生技术实现元素的分离，与质谱联用发展低空白、高灵敏的同位素分析的新方法。

项目围绕介质阻挡放电、液体电极放电等常压低温等离子体开展了一系列工作，发展了新型的等离子化学蒸气发生方法，研制了新型的微等离子体激发源，实现了Cd、Zn、Pb、Hg等元素的灵敏分析。具体主要包括以下几个方面：1）发展了液膜介质阻挡放电等离子体化学蒸气发生方法，实现了Zn的冷蒸气发生检测，而且发现了通过非离子型表面活性剂可以显著增强蒸气发生效率，从而改善了Cd、Zn等元素的蒸气发生效率；2)提出了基于等离子体电化学的蒸气发生新模式，对比了等离子体电化学和常规电化学发生的不同以及新方法的优势，与液膜介质阻挡放电相比，避免了氢气的使用，而且可以在高的电子利用效率下实现Cd、Zn的等离子体电化学蒸气发生，并初步探讨了发生的机理；3）建立了液体喷雾介质阻挡放电蒸气发生方法，较好地解决了等离子体蒸气发生方法中共存离子的干扰问题，而且显著的拓宽了等离子体化学蒸气发生的范围；最后我们还考察了不同元素形态蒸气发生的可行性，并将发展的等离子体蒸气发生与MC-ICPMS联用初步实现了Pb、Cd的同位素分析。4）发展了新型的辉光放电激发源，在低功耗下实现As、Sb等元素的灵敏检测，并研制了辉光放电微等离子体源便携式重金属监测仪器样机；5）建立了基于薄层色谱的纳米颗粒分析新方法。项目执行期间共以第一作者或通讯作者发表基金标注的SCI期刊论文16篇，其中Analytical Chemistry 4篇，Journal of Analytical Atomic Spectrometry封面论文2篇；获得授权发明专利2项。