质谱中气相离子远电荷碎裂反应研究进展

本文综述了质谱中气相离子在碰撞诱导解离谱中的远电荷碎裂反应研究进展,包括反应机理、内能估计和有机分析上的应用等,并在实验和理论上证明了极低碰撞能下远电荷碎裂反应的可能性。远电荷碎裂反应已成为区分某些有机异构体组分很方便的仪器分析方法。     

[C12H8]^2＋离子中电荷定位的理论研究

本文用半经验量子化学方法ＭＮＤＯ研究了由联苯衍生物产生的［Ｃ１２Ｈ８］２＋双电荷离子的结构，讨论了其中的电荷定位和影响离子稳定性的因素，双电荷离子的两个电荷分别定位于两个苯环上，表明该离子是由联苯衍生物经两步反应产生。     

电荷放大器的漂移问题

低频范围内的测量或可称为准静态测量。本文将就传感器和电荷放大器在准静态里的测量进行讨论,并就电荷放大器的漂移问题,时间常数及频率影响进行论述。1.传感器压电传感器是一种能量转换器,属于发电型的传感器,其输出量是电荷,也可以是电压信号。如果传感器是利用石英晶体二端     

极化方法对聚丙烯无纺布电荷储存能力的影响

研究恒流和恒压两种电晕充电方法极化后的聚丙烯(Polypropylene,PP)无纺布驻极体的电荷储存能力,以及极化参数对电荷稳定性的影响.结果表明,恒压电晕充电的样品具有较好的电荷稳定性,而恒流电晕充电的样品能储存较高的电荷密度.高温充电可以明显地改善聚丙烯无纺布的电荷稳定性.     

极化方法对聚丙烯无纺布电荷储存能力的影响

研究恒流和恒压两种电晕充电方法极化后的聚丙烯(Polypropylene,PP)无纺布驻极体的电荷储存能力,以及极化参数对电荷稳定性的影响.结果表明,恒压电晕充电的样品具有较好的电荷稳定性,而恒流电晕充电的样品能储存较高的电荷密度.高温充电可以明显地改善聚丙烯无纺布的电荷稳定性.     

基于USB接口的高精度电荷校准仪

采用虚拟仪器技术、直接数字合成技术和计算机技术设计了电荷校准仪,其工作状态由计算机USB接口控制,能输出多种波形的电压和电荷信号,电路中采用双DAC结构实现了幅值的精确控制.计量检验结果表明设计的电荷校准仪精度高、性能稳定,能够满足高精度的压电测试系统和电荷放大器的校准需要.     

电荷耦合器件调制传递函数测试方法的研究

本文在理论上系统阐述了用调制传递函数方法评价电荷耦合器件性能的可行性,分析讨论了电荷耦合器件调制传递函数的构成,系统研究了电荷耦合器件调制传递函数的测试方法。本文提出了测量方案,并详细介绍了系统的构成及软件设计,最后给出了测量结果。     

基于压电发电的同步电荷采集电路仿真

介绍了压电发电装置的理论及同步电荷提取技术，并使用PSIM软件进行电路仿真，分别对同步电荷提取电路及标准能量采集电路仿真，验证了理论分析的正确性。     

超电荷试剂在蛋白质紫外激光解离质谱表征中的应用研究

本文采用193 nm紫外激光解离质谱(UVPD-MS)研究非变性电喷雾条件下,超电荷试剂环丁砜对蛋白质序列、结构表征的影响。UVPD可在5 ns内对保持高级结构和非共价相互作用的不同价态碳酸酐酶进行快速激发解离,解离序列覆盖率达79.8%,具有较高的解离结构选择性。超电荷试剂环丁砜的引入可显著增加非变性电喷雾产生的碳酸酐酶离子的电荷数目,UVPD解离序列覆盖率提升至87.2%,实现对难解离区域的位点覆盖和序列、结构表征。加入环丁砜后,碳酸酐酶仍能保持高级结构谱学特征及与锌离子的非共价结合,锌离子结合区域等大部分结构区域的UVPD位点解离效率未见显著变化。但是,电荷数目的增加存在引起蛋白质局部结构变化的风险。     

静电电荷衰减测试研究现状及对策

从静电电荷衰减测试标准、方法、仪器以及国内外对测试方法的评价研究等几个方面,对静电电荷衰减测试的研究现状进行了分析,在此基础上,提出了解决相关问题的对策,明确了下一步的研究内容。     

Hydrated metal ions in the gas phase

Studying metal ion solvation, especially hydration, in the gas phase has developed into a field that is dominated by a tight interaction between experiment and theory. Since the studied species carry charge, mass spectrometry is an indispensable tool in all experiments. Whereas gas-phase coordination chemistry and reactions of bare metal ions are reasonably well understood, systems containing a larger number of solvent molecules are still difficult to understand. This review focuses on the rich chemistry of hydrated metal ions in the gas phase, covering coordination chemistry, charge separation in multiply charged systems, as well as intracluster and ion-molecule reactions. Key ideas of metal ion solvation in the gas phase are illustrated with rare-gas solvated metal ions.     

Electrospray: From ions in solution to ions in the gas phase,what we know now

There is an advantage for users of electrospray and nanospray mass spectrometry to have an understanding of the processes involved in the conversion of the ions present in the solution to ions in the gas phase. The following processes are considered: Creation of charge droplets at the capillary tip; Electrical potentials required and possibility of gas discharges; Evolution of charged droplets, due to solvent evaporation and Coulomb explosions, to very small droplets that are the precursors of the gas phase ions; Production of gas phase ions from these droplets via the Ion Evaporation and Charge residue models; Analytical uses of ESIMS of small ions, qualitative and quantitative analysis; Effects of the ESI mechanism on the analysis of proteins and protein complexes; Determination of stability constants of protein complexes; Role of additives such as ammonium acetate on the observed mass spectra. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:898–917, 2009     

双哌嗪盐类化合物电子轰击离子化质谱研究(英文)

对 6个新合成的双哌嗪盐类化合物进行了电子轰击离子化质谱及其裂解规律的研究。研究表明 :通过降低电子轰击电流强度 ,该类化合物的电子轰击离子化质谱的准分子离子和特征碎片峰非常清晰。但 M+和 M2 +离子峰并未出现。在低电子能量条件下 ,发现了 [M-2 ]+,[M-R]+,[M-R-1 ]+,[M-2 R]+,甚至 [RX]+离子峰的存在。这些现象可能与分子内的 R+重排反应有关。进一步尝试提出该类化合物的电子轰击离子化质谱裂解规律 ,为该类化合物的质谱研究提供有用的信息。     

A magnesium vapor charge-exchange target for an accelerator mass spectrometer

The target design and results of experiments aimed at stripping carbon ions in magnesium vapor are presented. It is proposed to substitute such a target for gas targets conventionally used in accelerator mass spectrometers, which will reduce the background ion charge exchange outside the target. Original Russian Text ? V.F. Klyuev, V.V. Parkhomchuk, S.A. Rastigeev, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 2, pp. 101–104.     

Recent developments in the ion/ion chemistry of high-mass multiply charged ions

The ability to form multiply charged high-mass ions in the gas-phase, most notably via electrospray ionization (ESI), has allowed the study of many different combinations of positively and negatively charged ions. The charged products are directly amenable to study with mass spectrometry. Ion/ion reactions have proved to be "universal" in the sense that the high exothermicities and large rate constants associated with essentially any combination of oppositely charged ions lead to reaction regardless of the chemical functionalities associated with the ions. These characteristics make ion/ion reactions potentially analytically useful provided reagent ion densities and spatial overlap of the oppositely charged ions are high. These conditions can be readily met by several instrumental configurations. The focus of this review is to highlight developments in this field since 1998. Novel instrumentation has been developed to study ion/ion reactions, such as atmospheric pressure ion/ion reactors followed by mass analysis, or electrodynamic ion trap mass spectrometers, which are used as reaction vessels at sub-atmospheric pressures. A wide variety of reaction phenomenologies have been observed in various ion/ion reactions, with proton transfer being the most common. New phenomenologies have been observed in the reactions of multiply charged positive ions with singly charged negative ions, including cation transfer and cation exchange. A new series of reactions between multiply charged positive ions and multiply charged negative ions have been made possible by recent instrumentation developments. These reactions have led to the observation of proton transfer and complex formation. These observations have provided new insights into ion/ion reaction dynamics and a bound orbit model appears to best account for experimental results. New applications are also discussed for a several ion/ion reaction.     

稀土异羟肟酸配合物的快原子轰击质谱研究

本文报道了两类稀土异羟肟酸配合物的正、负离子快原子轰击质谱（ＦＡＢＭＳ），通过分析ＦＡＢＭＳ特征离子讨论了配合物溶液中的配体交换反应及离解反应。     

Mass spectrometric glycan rearrangements

Mass spectrometric rearrangement reactions have been reported for a large variety of compounds such as peptides, lipids, and carbohydrates. In the case of carbohydrates this phenomenon has been described as internal residue loss. Resulting fragment ions may be misinterpreted as fragments arising from conventional glycosidic bond cleavages, which may result in incorrect structural assignment. Therefore, awareness of the occurrence of glycan rearrangements is important for avoiding misinterpretation of tandem mass spectra. In this review mass spectrometric rearrangements of both derivatized and underivatized (native) oligosaccharide structures are discussed. Similar phenomena have been reported for glycopeptides, labeled glycan structures and other biomolecules containing a carbohydrate part. Rearrangements in oligosaccharides and glycoconjugates have been observed with different types of mass spectrometers. Most of the observed carbohydrate rearrangement reactions appear to be linked to the presence of a proton. Hence, tandem mass spectrometric analysis of alkali adducts or deprotonated ions often prevents rearrangement reactions, while they may happen with high efficacy with protonated glycoconjugates.     

基于离子/中性复合物中间体介导的气相离子反应研究

离子/中性复合物（Ion-neutral complex,INC）是单分子气相反应的重要中间体。近20年来,各国科学家已经相继报道了多类离子/中性复合物参与的质谱裂解反应,包括质子转移反应、阳离子转移反应以及多种重排反应等^[1-4]。 在质子化芳基醚、苯磺酰胺等几类化合物的多级质谱中,观察到一系列以离子/中性复合物为中间体的气相离子裂解反应,包括一类新的电子转移反应^[5],这些裂解反应形成产物离子的途径、以及产物离子的丰度均与取代基效应有关。我们通过理论计算和氘代实验系统研究了这些反应。     

基于傅里叶变换离子回旋共振质谱仪(FT ICR MS)的超宽波段光解离光谱系统的研制及应用

基于质谱技术的光解离光谱方法具有灵敏度高和可行性好的优势,近年来在气相离子化学和分析化学研究领域得到了快速发展和广泛应用。本工作基于一台7 T的傅里叶变换离子回旋共振质谱仪(FT ICR MS),搭建了超宽波段的可调谐激光光路系统,获得了气相离子超宽波段的光解离光谱。该系统的光谱可调谐范围为192~3 700 nm,是目前已知在单台质谱仪上可获得最宽波段的光解离光谱系统。超宽波段的波长覆盖范围使用两台宽波段可调谐OPO激光器实现,光路可以在真空传输,提高了紫外和红外激光的传输效率。该系统结合了电喷雾(ESI)电离源和FT ICR MS的高分辨能力以及超强的离子操控能力,可以获得目标离子的紫外-可见光以及中红外区域的光解离光谱,分别对应于分子的电子和振动能级,实现了分子结构信息的互补。以罗丹明110和色胺为例,获得了相应的离子在不同波段中的光解离光谱,初步证明了该仪器实现相关功能的可行性。     

电喷雾萃取电离和电喷雾电离所获一价正离子内能差异的比较研究

电喷雾萃取电离（EESI）和电喷雾电离（ESI）均属于软电离技术,但EESI比ESI更温和,能更好地保持蛋白质的构象。本研究以一价正离子为例,分别采用EESI和ESI技术对罗丹明B准分子离子m/z 443的裂解行为进行多级串联质谱研究,考察了不同碰撞能量对裂解行为的影响,建立了这两种离子源产生的离子内能差异（简称内能差异）的定量测定方法,并探讨了该方法的影响因素及适用范围。结果表明,EESI与ESI离子源的内能差异为11.5 eV。该方法可为其他不同离子源产生的离子内能差异比较提供基本思路,也可为深刻理解不同离子源产生离子的质谱行为提供参考。