Development of a SIMION-Simulated Ion Funnel Tube for Proton Transfer Reaction Mass Spectrometry

Because the optimum working pressure of ion funnel (IF) is very close to the typical operating pressure of a traditional drift tube for proton transfer reaction mass spectrometry (PTR-MS), it is possible to develop an IF drift tube for PTR-MS to improve the sensitivity. In this study, an ion funnel capable of functioning as a drift tube in a PTR-MS system was designed and studied by computer simulation. To optimize the geometrical and electrical parameters of the ion funnel, five ion funnel configurations were constructed. The merits and features of the respective ion funnels were evaluated, and the ion transmission characteristics were investigated and analyzed. An optimized ion funnel model was compared against the typical traditional drift tube that was used in PTR-MS for ion transmission, and it was found that the ion traveling trajectories in the ion funnel and traditional drift tube had different shapes and ion transmission efficiencies. Preliminary investigations revealed that this ion funnel improved the ion transmission efficiency by at least 10 times. The simulation and experiment results are helpful in guiding the design of an improved ion funnel to develop a PTR-MS system with higher sensitivity.     

Ion mobility–mass spectrometry: a new paradigm for proteomics

Matrix-assisted laser desorption/ionization (MALDI) coupled with ion mobility–mass spectrometry (IM–MS) provides a rapid (μs–ms) means for the two-dimensional (2D) separation of complex biological samples (e.g., peptides, oligonucleotides, glycoconjugates, lipids, etc.), elucidation of solvent-free secondary structural elements (e.g., helices, β-hairpins, random coils, etc.), rapid identification of post-translational modifications (e.g., phosphorylation, glycosylation, etc.) or ligation of small molecules, and simultaneous and comprehensive sequencing information of biopolymers. In IM–MS, protein-identification information is complemented by structural characterization data, which is difficult to obtain using conventional proteomic techniques. New avenues for enhancing the figures of merit (e.g., sensitivity, limits of detection, dynamic range, and analyte selectivity) and optimizing IM–MS experimental parameters are described in the context of deriving new information at the forefront of proteomics research.     

Progress of Sonic-Spray Ionization Mass Spectrometry and Its Applications

Sonic-spray ionization (SSI) is a previously developed soft ionization technique which does not need auxiliary methods such as voltage, heating, laser, or corona discharge. Spray ionization can be achieved under normal temperature and atmospheric pressure by inputting high-speed gas coaxial within the capillary. As an atmospheric pressure ion source, this technique was widely used as the interface of liquid chromatography-mass spectrometry at the beginning of its development. Based on the principles of sonic-spray ionization, a variety of easy ambient sonic-spray ionization derived techniques have been developed, which can be used for the in-situ, rapid and real-time analysis of samples with little or without any sample pretreatment. In this paper, the principless and characteristics of sonic-spray ionization were elaborated, and the progress of its application in life sciences, food safety, forensic chemistry, reaction monitoring, and other related fields were summarized.     

Laser Desorption Ionization of Melamine and Identification of Fragmentation Channels from Ion Velocity Distribution Measurements

Fragmentation frequently accompanies intact laser desorption ionization of a parent non-volatile compound, desorption and dissociation dynamics has been a subject of intense studies over the past decade. As a preliminary lest system for future laser desorption study of energetic compounds such as explosives and propellents, we studied UV laser desorption ionization of melamine at a laser power density of approximately 4.4 MW/cm². Several gas-phase dissociation channels of the parent and fragment ions formed in UV laser desorption ionization of melamine films can be identified from their velocity distributions. A phenomenological desorption temperature of the order of 20000 K is estimated from fitting the experimental velocity distributions to Maxwellian functions.     

Ion chromatography-mass spectrometry: A review of recent technologies and applications in forensic and environmental explosives analysis

The development and application of ion chromatography (IC) coupled to mass spectrometry (MS) is discussed herein for the quantitative determination of low-order explosives-related ionic species in environmental and forensic sample types. Issues relating to environmental explosives contamination and the need for more confirmatory IC-MS based applications in forensic science are examined. In particular, the compatibility of a range of IC separation modes with MS detection is summarised along with the analytical challenges that have been overcome to facilitate determinations at the ng–μg L⁻¹ level. Observed trends in coupling IC to inductively coupled plasma and electrospray ionisation mass spectrometry form a particular focus. This review also includes a discussion of the relative performance of reported IC-MS methods in comparison to orthogonal ion separation-based, spectrometric and spectroscopic approaches to confirmatory detection of low-order explosives. Finally, some promising areas for future research are highlighted and discussed with respect to potential IC-MS applications.     

蛋白质半胱氨酸上的翻译后修饰组分析方法进展

半胱氨酸的巯基具有很高的反应活性,作为亲核、氧化还原催化反应、金属结合及变构调节位点等在蛋白质的结构和功能中发挥着非常重要的作用,且容易发生多种翻译后修饰,调控亦或损伤蛋白功能,与人类许多重要疾病关系密切,因此,定性与定量分析蛋白质半胱氨酸上的翻译后修饰组对理解其生物学功能具有重要意义。本文综述了近年来蛋白质半胱氨酸上常见的翻译后修饰组的质谱和蛋白质组学分析方法进展。     

Research Advances in Ion Channel-based Electrochemical Sensing Techniques

During the past few years, the electrochemical sensing techniques based on ion channels have attracted considerable attention. Nowadays, these techniques have been widely used in DNA sequencing, measurement of molecular interactions, and detection of inorganic ions and biological species. Hence, in this review, the research progresses of the ion channel-based electrochemical techniques including amperometry, conductometry and potentiometry in chemical and biological sensing are addressed from the perspective of different electrochemical methods. The sensing mechanism and fabrication process of these sensing methods are mainly introduced. In addition, the further research orientations of the electrochemical sensing based on ion channels are prospected.     

紫外可见分光光度技术的应用进展

介绍了近几年来紫外可见分光光度技术在仪器部件、多组分体系的测定,新技术应用进展以及与其他技术联用等方面的情况(引用文献33篇)。     

乐果乳油的离子淌度谱

对有机磷农药乐果乳油的离子淌度谱行为进行了研究，实验结果表明，质子高亲合能的氨水能较好地提高乐果乳油的检测选择性，当载气中分别加入多种混合溶剂，选择性可以得到进一步提高，其中以氨水和丙酮的混合溶剂选择性最好。     

Collisional Activation Mass Spectrometry—A New Probe for Determining the Structure of Ions in the Gas Phase

Organic ions with high translational energy colliding inelastically with neutral atoms or molecules become excited electronically at the expense of their translational energy. The excitation energy enables a wide range of dissociation reactions to occur and the intensity relationships yield information about the structure of the ions concerned and also permit conclusions to be drawn about the mechanism of their formation.     

On-line coupling of electrokinetic chromatography and mass spectrometry

The use of pseudostationary phases (PSPs) in capillary electrophoresis provides powerful separation systems of high efficiency, selectivity and flexibility. Such electrokinetic chromatographic (EKC) systems are particularly useful for chiral analysis or for the analysis of samples containing a broad range of compounds. As the availability of mass and/or structural data on (unknown) sample constituents is increasingly important, the on-line coupling of EKC and mass spectrometry (MS) has gained attention. However, commonly used PSPs, such as micelles and cyclodextrines, may strongly interfere with electrospray ionization (ESI), making on-line EKC–MS quite a challenging task. This review covers the various approaches that have been proposed and developed to combine EKC and MS. A distinction is made between methodologies that prevent the PSP from entering the MS system, and methodologies that allow introduction of PSPs into the ion source. Various approaches such as partial filling of the separation capillary with PSP, use of reverse-migrating PSPs, employment of volatile PSPs, and alternative ionization modes, are outlined. Specific applications are described and overview tables are provided. It is concluded that there is no general solution for EKC–MS available yet, but new ionization techniques like atmospheric pressure photoionization may offer attractive perspectives for achieving full compatibility.     

几种挥发性有机酚的离子淌度谱测定

应用离子淌度谱仪在负高压方式下测得苯酚、２－氯代酚、２，４－二氯代酚及五氯代酚的折合淌度值分别为２．１２、２．０１、１．９３、１．７４ ｃｍ２Ｖ－１ｓ－１，检测限分别为 １．０、０．１、０．５、０．５μｇ／Ｌ，２－氯代酚、２，４－二氯代酚的二聚体的折合淌度值分别为 １．６０、１．４７ｃｍ２Ｖ１ｓ１，并对苯酚、２－氯代酚和２，４－二氯代酚的混合物进行了分析测定，并讨论了淌度值与分子量、分子形状之间的关系。     

磷酸化肽富集新方法研究进展

对组成复杂的生物样品中的低丰度磷酸化肽进行预富集,能够消除高丰度非磷酸化肽等干扰组分,从而提高磷酸化肽在质谱分析中的灵敏度,获得更好的检出和鉴定结果.在磷酸化肽富集过程中,对磷酸化肽具有选择性亲和作用的富集材料是实现对磷酸化肽特异高效富集的关键,多种具有不同类型亲和作用的富集材料已在磷酸化肽富集研究中得到了应用;而在材料形貌、富集操作形式、磷酸化肽富集特异性等方面,研究者们也不断在现有磷酸化肽富集材料的基础上进行多样化的改进.本文分别从不同类型亲和作用的磷酸化肽富集材料以及磷酸化肽富集方法改进两方面,对近年来磷酸化肽富集方法的研究进展进行了评述.     

阶梯电极离子阱质量分析器的结构与性能

本研究从理论上优化了一种新型结构的线型离子阱质量分析器-阶梯电极离子阱质量分析器,它是由2对阶梯电极与1对端盖电极组成。与传统平板电极矩形离子阱长阶梯电极离子阱相比,具有调节电场分布的优点,同时在几何结构设计上更接近于双曲面电极结构,但比双曲面电极更容易加工。通过改变阶梯电极结构的高度、宽度、场半径比例等几何参数,实现了对离子阱内部电场分布的优化,从而实现离子阱性能的优化。理论模拟研究结果表明,根据几何结构和电场分布优化获得的阶梯电极离子阱质量分析器(X0×Y0=9 mm×5 mm),可以在225 Da/ s 扫速下获得10150的质量分辨率。阶梯电极离子阱结构简单,分辨能力明显高于矩形离子阱。初步的实验结果表明,阶梯电极离子阱具有较好的串级质谱分析性能。     

高氯酸锂甲醇溶液中离子溶剂化和离子缔合现象

通过红外光谱技术探讨了高氯酸锂甲醇溶液中离子与溶剂、离子与离子之间的相互作用。红外光谱分析结果表明:锂离子与溶剂发生了相互作用导致甲醇分子的O-H伸缩振动区蓝移,ClO4-的特征谱带的变化表明了溶液中存在离子缔合。根据密度泛函理论,对不同溶剂化数的配合物结构和两种离子对形式进行优化及热力学性质的计算。     

State of Art in the SIMS (Secondary Ion Mass Spectrometry) Application to Archaeometry Studies

One of the main problems of cultural heritages in all the different forms (buildings, monuments, painting) is their deterioration caused by natural and artificial decay processes. To address the conservation issue specific studies are required to determine, for example, origin, date, materials composition, technology processes involved, etc. The use of microanalysis techniques, in particular secondary ion mass spectrometry (SIMS), in the cultural heritage area has been demonstrated extremely useful to approach and provide this kind of information and support the experts involved in studies within this area (art historians, archaeologists, curators etc.). In this work, an up to date overview of possible SIMS applications to archaeological topics is given, pointing out the peculiarity and the main limitations and drawbacks of this analytical approach. One example of SIMS application to archaeological glasses is reported. Moreover the wide technique flexibility and its strength in combination with other complementary techniques are remarked.     

接枝共聚物分子设计及合成方法研究进展

接枝共聚物的主链和支链通过分子设计可以被赋予不同性质,从而使得材料拥有两种截然相反的性能.新的接枝合成方法的产生又增加了各种复杂分子结构设计的可实现性.本文围绕接枝共聚物所具有的独特结构和性能特点,详细介绍了近年来接枝共聚物在分子链和星型侧链等方面的研究现状,同时介绍了连接化学,原位氯化接枝共聚等合成方法在接枝共聚合中的应用进展,并展望了接枝共聚物的发展前景.     

离子淌度谱及其近年进展

近年来离子淌度谱（ＩＭＳ）在样品引入技术，信号采集和数据处理、离子源等方面都有了显著的进展，其中以ＩＭＳ作为色谱检测器（ＩＭＤ）进行的研究尤为重要，而ＩＭＳ与Ｊ民喷雾郭子化（ＥＳＩ）技术的联用扩大其在非挥发性化合物和生物物质检测方面的应用评论还综述了近年来ＩＭＳ应用于环保、化学化工、违禁药物检测、爆炸物检测以及半导体表面挥发物分析等方面的最新研究成果。     

微波诱导等离子体离子迁移谱仪性能及影响因素的研究

离子迁移谱仪的性能受到多种因素的影响,如漂移管电场强度离子门脉冲宽度、离子源工作条件、漂移管尺寸、离子门加工工艺和屏蔽网透过率等。在实际应用中需要对漂移管电场强度和离子门脉冲宽度进行调整以平衡灵敏度和分辨率。本研究详细研究了漂移管电场强度和离子门脉冲宽度对微波诱导等离子体离子迁移谱( MIPI-IMS)分辨率和灵敏度的影响。实验结果表明,存在一个最佳电场强度值使得分辨率达到最大,而且不同离子门脉冲宽度对应的最佳电场强度值不同;增大电场强度和离子门脉冲宽度有利于灵敏度的提升。与其它离子流较弱的离子源相比,离子流较大的微波诱导等离子体离子源在实际应用中对离子门脉冲宽度和漂移管电场强度有更多的选择。此研究结果有助于MIPI-IMS仪器性能的提升。将异丙醇用于测试MIPI-IMS的性能,结果表明,MIPI-IMS在保持较低检出限(7.7×10-11, V/V)的同时,分辨率可以达到66。     

原子吸收及原子荧光光谱分析

本文是《分析试验室》期刊定期评述中关于原子吸收光谱 (AAS)及原子荧光光谱 (AFS)分析的第 9篇综述文章。文中对 2 0 0 0年 12月～ 2 0 0 2年 11月期间我国在AAS AFS领域所取得的主要进展进行评述。内容包括概述、仪器装置、火焰原子吸收光谱法、电热原子吸收光谱法、化学蒸气发生技术以及原子荧光光谱法等。收集文献 35 8篇。