Elemental, Micro, Ultra Trace Analysis

德克萨斯大学奥斯汀分校的James Holcombe教授在分析和表面化学项目的支持下进行微量元素分析研究。具体来说，研究了两个领域：电热汽化（ETV）样品引入电感耦合质谱仪（ICPMS）和冷原子原子吸收溶液光谱法（CAAASS）。这个想法是发展分析方法，其中矩阵的复杂性不会干扰分析。ETV-ICPMS采用微样品，并且对基质没有样品引入限制，即具有高溶解盐，浆液和固体含量的样品都可以使用，而无需稀释或消化。样品吞吐率，传输效率和等离子体负载（因为复杂的矩阵）是解决的问题。一种低功耗、基于石墨的灯丝系统正在开发，以取代传统的管式设计或金属灯丝蒸发器。确保气溶胶从ETV到ICP的可重复运输效率是使用微孔石墨管和方法将气溶胶集中在流向ICP的气体中的动机。ETV的热斜坡提供了一个简单的色谱（热）分离装置，以廉价的方式帮助识别和规避干扰，并优化瞬时信噪比。虽然已经证明了ETV-ICP飞行时间质谱的概念验证，但这项工作的重点是该方法的全部含义和局限性。提出了气溶胶分散的基础研究和混合气体等离子体的应用。CAAASS是一种在室温下在溶液中产生原子的新方法，首先在Sturgeon的实验室中作为样品导入ICP的工具进行了演示。Holcombe的实验室将研究这些非常有趣现象的基本原理，并将其应用于通过微芯片中的二极管激光原子吸收进行元素分析的方法。元素分析仍然是现代研究和发展的基石。在生物领域，它的应用范围从辅助因子浓度的基本测定到药物的药效学评价（如抗癌药物中的铂）。由于其毒性，许多金属仍然是生物积累的焦点。水、土壤和空气分析仍然活跃，因为这些通常是污染的再循环来源，其影响水平极低。基础地质科学也依赖金属作为示踪剂。虽然存在许多可行的基本超痕量元素检测方法，但处理复杂矩阵中包含的微样品的技术需要花费数千小时的精力来设计方法，其中许多方法仅对特定应用有用。这项研究试图为更广泛的研究界提供一种最具成本效益的工具，使研究能够在许多科学和医学领域取得进展。

Professor James Holcombe of the University of Texas Austin is supported by the Analytical and Surface Chemistry Program for research on microanalytical trace elemental analysis. Specifically, two areas are addressed: electrothermal vaporization (ETV) sample introduction into an inductively coupled mass spectrometer (ICPMS) and cold atom atomic absorption solution spectrometry (CAAASS). The idea is to develop analytical methods where the complexity of the matrix will not interfere with the analysis. ETV-ICPMS employs microsamples and places no sample introduction restrictions on the matrix, i.e., samples with high levels of dissolved salts, slurries and solids can all be used without dilution or digestion. Sample throughput rates, transport efficiencies and plasma loading (because of the complex matrix) are problems that are addressed. A low power, graphite-based filament system is being developed in lieu of the classical tube design or metal filament vaporizer. Insuring reproducible transport efficiency of the aerosol from the ETV to the ICP is the motivation behind the use of a microporous graphite tube and methodologies to center the aerosol in the gas flowing to the ICP. The thermal ramp of the ETV provides a crude chromatographic (thermal) separation device to inexpensively assist in discerning and circumventing interferences as well as optimizing the instantaneous signal to noise ratio. Although the proof-of-concept for ETV-ICP time-of-flight mass spectrometry has been demonstrated, this work focuses on the full implications and limitations of the method. Fundamental studies of aerosol dispersion as well as use of mixed gas plasma are also proposed. CAAASS is a novel means of generating atoms at room temperature in solution that was first demonstrated in Sturgeon's laboratory as a tool for sample introduction into an ICP. Holcombe's laboratory will investigate the fundamentals of these very interesting phenomena with the application goal of using the approach for elemental analysis via diode laser atomic absorption in a microchip. Elemental analysis remains a cornerstone in modern research and development. In the biological world, its use range from basic determination of cofactor concentrations to pharmokinetic evaluations of drugs (e.g. platinum in anticarcinogens). Because of their toxicity, many metals remain the focus of bioaccumulations. Water, soil and air analysis remains active since these are often the recirculating source of pollution and show impacts at exceedingly low levels. Basic geological sciences also rely on metals as tracers. While many viable approaches exist for basic ultratrace elemental detection, techniques for dealing with microsamples contained within a complex matrix consumes thousands of hours of effort to design methods, many of which are unique and useful only for the particular application. This research attempts to provide the broader research community with a tool that will most cost-effectively permit research to advance in a number of scientific and medical areas.