ELECTRON MONOCHROMATOR TIME-OF-FIGHT MASS SPECTROMETER

电子单色仪战斗时间质谱仪

• 批准号: 6382263
• 负责人: MAX L DEINZER
• 金额: $ 14.04万
• 依托单位: OREGON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2003-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6382263
• 关键词: analytical method; bioengineering /biomedical engineering; clinical biomedical equipment; mass spectrometry; nonbiomedical equipment; technology /technique development

The interaction of low-energy electrons with electrophilic molecules in the production of negative ions is an important chemical process. Electron capture negative ion mass spectrometry (ECNI-MS) is a powerful system used for the analysis of very small amounts of such compounds, but in its present forms it can provide only limited information on the processes that produce negative ions. In this application we propose to construct a versatile gas chromatography/electron monochromator-time-of- flight mass spectrometer (GC/EM-TOF-MS). This instrument will be used to elucidate mechanisms of negative ion formation and decomposition via metastable ions. The electron monochromator (EM) to be used generates monoenergetic electron beams with currents of approximately 400 microamps tunable in the range 0- 15eV with maximum energy spreads of O.leV. The electron source when interfaced to the time-of-flight (TOF) analyzer will yield reproducible 3-dimensional spectra whose axes are resonance electron energy mass to charge, and ion signal intensity. The gas chromatographici nlet system, will provide a means to resolve compound mixtures and a stable supply of buffer gas to stabilize resonance electron capture ions. A reflectron in the analyzer will provide the capability to study metastable ions. Experimental resonance electron energies, when correlated with the virtual orbital energies of the molecules calculated by density functional theory methods, will provide information on the orbitals involved during initial ion formation. Electron attachment to several classes of electrophilic compounds including organophosphates, sulfonamides, dinitro [2,2]para- cyclophane, aliphatic ketones, haloethenes, vinyl chloride and chloroacetaldehyde will be investigated. In addition to providing a unique system for studying the mechanistic details of negative ion formation, the sensitivity, specificity, extra dimension of analytical information from resonance electron energies and "fast" GC/MS capability of the proposed GC/EM-TOF MS instrument will make it a valuable new tool for analyzing environmental health-related chemicals, biochemical and biomedical-related compounds that can be derivatized with electrophores. The analysis of proteins, peptides and other biopolymers with electron-capturing posttranslational modifications is another potentially exciting application for the GC/EM-TOF-MS system.

低能电子与亲电分子的相互作用是产生负离子的重要化学过程。电子捕获负离子质谱（ECNI-MS）是一种用于分析极少量此类化合物的强大系统，但以其目前的形式，它只能提供产生负离子过程的有限信息。在这个应用中，我们建议建立一个通用的气相色谱/电子单色-飞行时间质谱仪（GC/EM-TOF-MS）。该仪器将用于阐明通过亚稳离子形成和分解负离子的机制。所使用的电子单色仪（EM）产生的单能电子束电流约为400微安，可在0- 15eV范围内调节，最大能量扩展为O.leV。当电子源与TOF （time-of-flight）分析仪连接时，将产生以共振电子能量、电荷质量和离子信号强度为轴的可再现的三维光谱。气相色谱仪系统，将提供一种手段，以解决化合物混合物和缓冲气体的稳定供应，以稳定共振电子捕获离子。分析器中的反射器将提供研究亚稳离子的能力。当实验共振电子能量与密度泛函理论方法计算的分子虚轨道能量相关联时，将提供初始离子形成过程中涉及的轨道信息。将研究几种亲电化合物的电子附着，包括有机磷酸盐、磺胺类、二硝基[2,2]对环烷、脂肪族酮、卤乙烯、氯乙烯和氯乙醛。除了为研究负离子形成的机理细节提供了一个独特的系统外，所提出的GC/EM-TOF质谱仪的灵敏度、特异性、共振电子能量分析信息的额外维度和“快速”GC/MS能力将使其成为分析环境健康相关化学品、生化和生物医学相关化合物的有价值的新工具，可以通过电泳衍生。具有电子捕获翻译后修饰的蛋白质、多肽和其他生物聚合物的分析是GC/EM-TOF-MS系统的另一个潜在的令人兴奋的应用。