仪器装置与实验技术小型矩形离子阱质谱仪的研制

研制的小型质谱仪以电子轰击源(EI)和矩形离子阱(RIT)质量分析器为核心部件,采用渗透阀控制的直接进样系统,高增益的电子倍增器用于离子检测,通过小信号放大系统对电子倍增器输出的弱电流再次放大,并输出电压信号,计算机上的NI数据采集卡和Labview操作软件对电压信号进行采集处理。由旋片机械泵和分子泵组成的真空系统可以形成10-5Pa的质谱工作环境。对研制的仪器进行了初步测试,得到了相应的质谱图,通过质量校正表明,结果令人满意。     

便携式气相色谱-质谱联用仪的研制及应用

将双曲面三维离子阱质谱技术与低热容气相色谱技术相结合,研制了便携式气相色谱-质谱联用仪(GC-MS).此仪器主要由进样系统、低热容气相色谱模块、气质接口以及小型化离子阱质谱模块等构成,其主机重量小于14 kg,体积为44 cm×36 cm×22 cm,功耗小于100W.该仪器中的离子阱质谱仪系统具有15～550 amu...     

数字离子阱质谱仪低质量截止值的改进方法

本研究在实验室自制的线形数字离子阱质量分析器上,通过改变数码电源的频率扫描方式,在CID过程中,通过扫描数字束缚方波电源的频率和数字激发方波的频率实现母体解离。例如对于利血平母体离子,当将离子数字束缚方波频率从500 kHz扫描到560 kHz,可以测量到低质荷比的碎片离子,成功实现了串级质谱分析的低质量碎片离子的分析。通过与利血平三重四极质谱串级质谱分析实验结果的比较,发现可以在数字离子阱质谱仪上获得与三重四极质谱相同的串级质谱测量结果。结果表明,本方法可以用于低质量离子的测量,克服了传统离子阱质谱进行串级质谱分析的一个主要难点,显著提高数字离子阱质谱的性能。     

数字化矩形离子阱质谱仪的设计及性能

将数字化离子阱技术和矩形离子阱(RIT)技术相结合,建立了数字化矩形离子阱质谱仪.此技术和装置既具有数字化电源的结构简单、输出稳定和易精确控制等特点,又结合了矩形离子阱的高离子存储效率、结构简单以及加工和装配容易等优点.构建了基于电喷雾(ESI)电离源的数字化矩形离子阱质谱仪系统,并使用Fenfluramine和PPG2000分别对此系统的质量分辨率和质量范围进行了测试.研究结果表明:一个用印刷线路板(PCB)制作的简单矩形离子阱,在200 V(半峰值)的数字束缚电压的驱动下,获得了大于500的质量分辨率和超过2600 Th的质量范围.实验证明,数字化离子阱技术的应用可以显著提高矩形离子阱的性能,特别是质量范围等关键的质谱仪指标.     

质谱仪器及其发展

本文按照进样系统、离子源、质量分析器、检测器的顺序 ,介绍质谱仪器的构造 ,并对其性能进行简要评述 ,指出质谱仪器的发展方向及其对国防、航天以及其他工业、民用等诸多领域的重要意义     

离子阱颗粒质谱研究进展

随着质谱技术的不断发展,对超高质量颗粒物质的分析已经成为质谱领域研究的一个重要方向.离子阱颗粒质谱(particle ion trap mass spectrometry)作为用于完整颗粒质量分析的有利工具,拓展了质谱技术在巨大颗粒物质量分析中的应用范围.本文对离子阱颗粒质谱仪器的研究进展及其在各个领域的应用进行了综述,并展望了离子阱颗粒质谱未来的发展趋势.     

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。     

“二次离子质谱仪器核心技术研发”项目子课题通过验收

2月21至22日,由国家质检总局科技司委托组成的测试专家组,对中科院大连化学物理研究所承担的“十一五”国家科技支撑计划项目课题“二次离子质谱仪器核心技术及关键部件研究与开发”中的子课题“角反射飞行时间质量分析器”进行了现场考核与测试.     

栅网电极离子阱质量分析器的结构与性能

报道了一种结构非常简单的新型线型离子阱质量分析器,它由4块"栅网电极"电极与2块端盖电极合围而成的一个近似于长方体的离子存储和分析空间。"栅网电极"的结构为:首先在矩形电极上加工一个"口"字型的通孔,然后再用导电的栅网覆盖住"口"字表面构成。这4块含有栅网的电极合围成一个四面对称的长方体空间,它们与二个端盖电极组成一个完整的离子阱。用栅网电极构成离子阱质量分析器具有以下优势:(1)结构非常简单。它可以极大地减小离子阱质量分析器对组成离子阱电极的机械加工精度要求,如电极对称性,离子引出孔的线性度与大小,以及对离子阱组装精度的要求,使离子阱质谱的生产工艺和使用维护更加简化;(2)由于传统离子引出电极上的离子引出槽被省去,使得离子阱电极的对称性提高,这有可能改善离子阱内部的电场分布,提高离子阱质量分析器的质谱性能;(3)由于离子引出电极的大部分为栅网,它可以成倍提高离子引出效率,提高质谱仪的分析灵敏度。初步的实验结果表明,用本工作给出的用栅网电极组成的离子阱质量分析器,当栅网宽度为4 mm时,在较低的离子共振激发电压下,即可将离子从阱中弹出,并可以获得高于400的质量分辨率和300 Thomson以上的质量扫描范围。     

Development of a palm portable mass spectrometer

A palm portable mass spectrometer (PPMS) has been developed with a weight of 1. 48 kg (3 lb) and a size of 1.54 L (8.2 × 7.7 × 24.5 cm³) that can be operated with an average battery power of 5 W. A miniaturized ion trap has been used as a mass analyzer that consists of four parallel disks with coaxial holes. A rf voltage of 1500 V _p-p at 3.9 MHz has been used for scanning ion mass of up to m/z 300. An ion-getter pump serves for high vacuum of the PPMS. Sample gas was introduced in pulse mode. An embedded microcomputer has been developed for system control. Detection of organic gases diluted in the air has been demonstrated up to 6 ppm for toluene and 22 ppm for dimethyl methylphosphonate (DMMP). Performance results suggest usefulness of the PPMS as a personal mobile device for detection/identification of chemical warfare agents in the field.     

Three-dimensional concentration mapping of gases using a portable mass spectrometer system

The visualization of hazardous gaseous emissions at volcanoes using in-situ mass spectrometry (MS) is a key step towards a better comprehension of the geophysical phenomena surrounding eruptive activity. In-situ data consisting of helium, carbon dioxide, sulfur dioxide, and other gas species, were acquired with a quadrupole based MS system. Global position systems (GPS) and MS data were plotted on ground imagery, topography, and remote sensing data collected by a host of instruments during the second Costa Rica Airborne Research and Technology Applications (CARTA) mission. This combination of gas and imaging data allowed three-dimensional (3D) visualization of the volcanic plume and the mapping of gas concentration at several volcanic structures and urban areas. This combined set of data has demonstrated a better tool to assess hazardous conditions by visualizing and modeling of possible scenarios of volcanic activity. The MS system is used for in-situ measurement of 3D gas concentrations at different volcanic locations with three different transportation platforms: aircraft, auto, and hand-carried. The demonstration for urban contamination mapping is also presented as another possible use for the MS system.     

Direct monitoring of toxic compounds in air using a portable mass spectrometer

A portable tandem mass spectrometer, capable of performing atmospheric pressure chemical ionization (APCI) using a direct atmospheric inlet, is applied to the real-time monitoring of toxic compounds in air. Analytes of interest include dimethyl methylphosphonate, arsine, benzene, toluene, pyridine and vinyl acetate. The detection, identification and quantification of organic and inorganic compounds in air is demonstrated using short analysis times (<5 seconds) with detection limits in the low ppb (v/v) levels and linear dynamic ranges of several orders of magnitude. Highly specific detection and identification is achieved, even when the analyte is a trace component in a complex mixture including such interferents as fuels, lubricants, and cleaners. The effects of environmental conditions, including temperature and humidity, are delineated. Receiver operating characteristic (ROC) curves are presented to show the trade-off between false positive and false negative detection rates. Tandem mass spectrometry based both on collision-induced dissociation and on selective atmospheric pressure ion/molecule reactions is also used to increase selectivity and sensitivity.     

Field testing of lake water chemistry with a portable and an AUV-based mass spectrometer

Two mass spectrometers (MS) are tested for the measurement of volatile substances, such as hydrocarbons and metabolic gases, in natural waters. KOALA is a backpackable MS operated from above the water surface, in which samples are pumped through a flow cell using a syringe. NEREUS is an underwater instrument hosted by an autonomous underwater vehicle (AUV) that is linked to a communications network to provide chemical data in real time. The mass analyzers of the two MS are nearly identical cycloids, and both use flat-plate membrane inlets. Testing took place in an eutrophic, thermally stratified lake exhibiting steep chemical gradients and significant levels of methane. KOALA provided rapid multispecies analysis of dissolved gases, with a detection limit for methane of 0.1 ppm (readily extendable to 0.01 ppm) and savings of time of at least a factor of 10 compared to that of conventional analysis. The AUV-mounted NEREUS additionally provided rapid spatial coverage and the capability of performing chemical surveys autonomously. Tests demonstrated the need for temperature control of a membrane inlet when steep thermal gradients are present in a water body, as well as the benefits of co-locating all sensors on the AUV to avoid interference from chemically different waters entering and draining from the free-flooding outer hull. The ability to measure dissolved volatiles provided by MS offers potential for complementarity with ionic sensors in the study of natural waters, such as in the case of the carbonate system.     

Desorption electrospray ionization with a portable mass spectrometer: in situ analysis of ambient surfaces

Desorption electrospray ionization (DESI) is implemented on a portable mass spectrometer and used to demonstrate in situ detection of active ingredients in pharmaceutical preparations, alkaloids in plant tissues, explosives, chemical warfare agent simulants and agricultural chemicals from a variety of surfaces; air monitoring applications using DESI are also introduced.     

Sub-miniature ExB sector-field mass spectrometer

A novel sub-miniature double-focusing sector-field mass spectrometer has been fabricated at the University of Minnesota using a combination of conventional machining methods and thin film patterning techniques typically used in the sensor technology industry. Its design is based on the mass separation capabilities of a 90 degrees cylindrical crossed electric and magnetic sector-field analyzer with a 2-cm radius, which under proper conditions is able to effectively cancel the angular and chromatic dispersion of the ion beam, thus improving the resolving power of the instrument. Simulations using finite element analysis and computer modeling were employed to verify and optimize the performance of the proposed instrument before and during its fabrication. The prototype was able to attain a resolving power of 106 full-width at half-maximum (FWHM), a detection limit close to 10 parts per million, a dynamic range of 5 orders of magnitude and a mass range up to 103 Da. Its overall size, including the magnet assembly, is 3.5 cm wide, 6 cm long and 7.5 cm tall, it weighs 0.8 kg, and its power consumption was measured to be 2.5 W. The performance of the instrument was found to be comparable to that of commercial residual gas analyzers, at a fraction of the cost. All these characteristics make this miniature mass spectrometer suitable for portable and low-cost analytical instrumentation.