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ELECTRON MONOCHROMATOR TIME-OF-FIGHT MASS SPECTROMETER

电子单色仪战斗时间质谱仪

基本信息

批准号：
6524880
负责人：
MAX L DEINZER
金额：
$ 14.02万
依托单位：
OREGON STATE UNIVERSITY
依托单位国家：
美国
项目类别：
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

项目摘要

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相互作用产生负离子是一个重要的化学过程。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，它只能提供有关产生负离子的过程的有限信息。在这个应用中，我们提出了一个多功能的气相色谱/电子单色谱飞行时间质谱仪（GC/EM-TOF-MS）。该仪器将用于阐明负离子形成和通过亚稳离子分解的机制。所使用的电子单色器（EM）产生单能电子束，其电流约为400微安，可在0- 15 eV的范围内调节，最大能量扩展为0.1eV。当电子源连接到飞行时间（TOF）分析仪时，将产生可再现的三维光谱，其轴是共振电子能量质荷比和离子信号强度。气相色谱入口系统将提供解析化合物混合物的手段和稳定供应的缓冲气体以稳定共振电子捕获离子。分析仪中的反射器将提供研究亚稳离子的能力。实验共振电子能量，当与密度泛函理论方法计算的分子的虚轨道能量相关时，将提供初始离子形成过程中所涉及的轨道的信息。电子附着到几类亲电化合物，包括有机磷酸酯，磺胺，二硝基[2，2]帕拉环芳，脂肪酮，卤代乙烯，氯乙烯和氯乙醛将被研究。除了提供一个独特的系统，用于研究负离子形成的机理细节，灵敏度，特异性，额外的维度的分析信息，从共振电子能量和“快速”GC/MS能力的建议GC/EM-TOF MS仪器将使其成为一个有价值的新工具，用于分析环境健康相关的化学品，生物化学和生物医学相关的化合物，可以衍生与生物。蛋白质、肽和其他具有电子捕获翻译后修饰的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。