A Novel 9.4 Tesla FTICR Mass Spectrometer with Improved Sensitivity,Mass Resolution,and Mass Range

Fourier transform ion cyclotron resonance (FTICR) mass spectrometry provides unparalleled mass measurement accuracy and resolving power. However, propagation of the technique into new analytical fields requires continued advances in instrument speed and sensitivity. Here, we describe a substantial redesign of our custom-built 9.4 tesla FTICR mass spectrometer that improves sensitivity, acquisition speed, and provides an optimized platform for future instrumentation development. The instrument was designed around custom vacuum chambers for improved ion optical alignment, minimized distance from the external ion trap to magnetic field center, and high conductance for effective differential pumping. The length of the transfer optics is 30% shorter than the prior system, for reduced time-of-flight mass discrimination and increased ion transmission and trapping efficiency at the ICR cell. The ICR cell, electrical vacuum feedthroughs, and cabling have been improved to reduce the detection circuit capacitance (and improve detection sensitivity) 2-fold. The design simplifies access to the ICR cell, and the modular vacuum flange accommodates new ICR cell technology, including linearized excitation, high surface area detection, and tunable electrostatic trapping potential.     

Improved Miniaturized Linear Ion Trap Mass Spectrometer Using Lithographically Patterned Plates and Tapered Ejection Slit

We present a new two-plate linear ion trap mass spectrometer that overcomes both performance-based and miniaturization-related issues with prior designs. Borosilicate glass substrates are patterned with aluminum electrodes on one side and wire-bonded to printed circuit boards. Ions are trapped in the space between two such plates. Tapered ejection slits in each glass plate eliminate issues with charge build-up within the ejection slit and with blocking of ions that are ejected at off-nominal angles. The tapered slit allows miniaturization of the trap features (electrode size, slit width) needed for further reduction of trap size while allowing the use of substrates that are still thick enough to provide ruggedness during handling, assembly, and in-field applications. Plate spacing was optimized during operation using a motorized translation stage. A scan rate of 2300 Th/s with a sample mixture of toluene and deuterated toluene (D8) and xylenes (a mixture of o-, m-, p-) showed narrowest peak widths of 0.33 Th (FWHM).

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四极杆质谱、串联质谱系统在测定血液中毒鼠强的应用

毒鼠强又名424,化学名称为四次甲基二砜四胺(C4H8O4N2S2),分子量240.6,是一种无色无味白色粉末状物质,难溶于乙醇,微溶于水,易溶于丙酮、苯、乙醚,性质稳定,投毒后,不易被人们察觉,一旦中毒,发作快,死亡率高.多数医院难确诊、治疗.目前,对其主要的鉴定法有GC、GC-MS和HPLC等.通常在对毒鼠强中毒的生物检材进行毒鼠强分析时,由于生物组织机体中存在的干扰物质(如脂肪酸、胆固醇等)种类繁多,经净化处理后,其残留量仍然很大,不仅干扰目标化合物的定性,更难进行定量测定.因此GC-MS在定性分析中具有明显优势,因而成为目前主要的分析方法.     

可移动激光质谱仪的研制与应用

激光质谱法是一种新的环境测污方法,具有高灵敏度、高选择性、多组分同时测量和快速实时的特点。本研究介绍了新近研制的可移动激光质谱仪的系统结构、各部分功能、原理以及主要技术指标。该仪器能在大气压下采样,并在设计过程中解决了记忆效应,使用输出波长248nm的KrF准分子激光器,可以对芳香烃进行多组分同时检测。该仪器对机动车尾气中苯系物含量的实时在线测量结果表明,尾气中含有苯、甲苯、二甲苯、三甲苯、萘、甲基萘等多种芳香烃污染物,检测的灵敏度达0．1mg／m^3,时间响应可达0．1s。     

用数字离子阱进行快速质量分析

利用数字离子阱技术进行样品的快速质量分析.在样品离子被引入离子阱的过程中,同时扫描数字射频工作电压的频率和离子共振偶极电压的频率,使得离子在进入离子阱质量分析器后,立即被相应的共振偶极电压所共振激发而逐出离子阱,并被离子探测器测量到.本方法相较于传统离子阱分析过程省去了离子引入、离子冷却和离子清空3个阶段,减少了约3/4的实验分析时间.通过对扫描速度、离子门电压参数的优化,数字束缚射频频率从1000～ 400 kHz线性扫描,扫描速度为2385 Th/s,离子门电压为9V,对利血平(m/z 609),精氨酸(m/z 174)等样品的进行测试,离子信号强度达到最优.结果表明,利用本方法可以获得与离子阱质量分析传统方法相同的质谱结果.     

飞行时间质谱仪新技术的进展及应用

本文介绍了近几年来发展应用于飞行时间质谱(TOF-MS)仪中的软电离技术.质子转移电离实现了可挥发性有机物的高灵敏度分析;真空紫外灯电离源体积小、简单,利于便携式仪器;电喷雾解吸电离在线、无损和灵敏度高,在公共安全方面具有很大的发展潜力,而且还可以直接用于活的生物体表面分析;大气压下的在线直接分析电离技术利用载气分子的激发态使得被分析化合物电离得到分子离子.针对不同的电离方法简单评述了其性能及应用,同时介绍了飞行时间质谱在串联方面的新发展,以及TOF-MS在仪器微型化方面的进展及其应用,并对飞行时间质谱仪今后的发展作了展望.     

飞行时间质谱仪新技术的进展及应用

本文介绍了近几年来发展应用于飞行时间质谱(TOF-MS)仪中的软电离技术。质子转移电离实现了可挥发性有机物的高灵敏度分析;真空紫外灯电离源体积小、简单,利于便携式仪器;电喷雾解吸电离在线、无损和灵敏度高,在公共安全方面具有很大的发展潜力,而且还可以直接用于活的生物体表面分析;大气压下的在线直接分析电离技术利用载气分子的激发态使得被分析化合物电离得到分子离子。针对不同的电离方法简单评述了其性能及应用,同时介绍了飞行时间质谱在串联方面的新发展,以及TOF-MS在仪器微型化方面的进展及其应用,并对飞行时间质谱仪今后的发展作了展望。     

Factorial Experimental Designs Elucidate Significant Variables Affecting Data Acquisition on a Quadrupole Orbitrap Mass Spectrometer

Instrument parameter values for a quadrupole Orbitrap mass spectrometer were optimized for performing global proteomic analyses. Fourteen factors were evaluated for their influence on data-dependent acquisition with an emphasis on both the rate of sequencing and spectral quality by maximizing two individually tested response variables (unique peptides and protein groups). Of the 14 factors, 12 factors were assigned significant contrast values (P?<?0.05) for both response variables. Fundamentally, when optimizing parameters, a balance between spectral quality and duty cycle needs to be reached in order to maximize proteome coverage. This is especially true when using a data-dependent approach for sequencing complex proteomes. For example, maximum ion injection time, automatic gain control settings, and minimum threshold settings for triggering MS/MS isolation and activation all heavily influence ion signal, the number of spectra collected, and spectral quality. To better assess the effect these parameters have on data acquisition, all MS/MS data were parsed according to ion abundance by calculating the percent of the AGC target reached for each MS/MS event and then compared with successful peptide-spectrum matches. This proved to be an effective approach for understanding the effect of ion abundance on successful peptide-spectrum matches and establishing minimum ion abundance thresholds for triggering MS/MS isolation and activation.

用于综合录井技术的在线快速气相色谱-四极杆质谱联用仪研制

研制了一种用于综合录井技术的在线快速气相色谱-四极杆质谱联用仪。采用隔膜泵直接抽取泥浆中脱出的气体样品直接引入气相色谱,通过气驱十通阀实现自动进样;快速分离后,样品中各组分依次进入四极杆质谱进行检测;四极杆质谱采用电子轰击源电离及选择离子扫描的方式,提供对碳氢化合物检测所需要的高灵敏度;仪器通过精确的时序控制实现周期循环进样分析,满足录井现场的实时监测需求。仪器采用安全易得的氮气作载气,对C1-C8烷烃、苯、甲苯、环己烷和甲基环己烷等油气组分进行快速在线分析,结果表明,C1-C5分析周期小于30 s,C1-C8周期小于85 s,最低检测浓度为0.0001%(V/V),线性范围高于5个数量级,适合于录井技术中油气组分分析。     

Tandem Time-of-Flight Mass Spectrometer with High Precursor Ion Selectivity Employing Spiral Ion Trajectory and Improved Offset Parabolic Reflectron

In this study, we have developed a tandem time-of-flight mass spectrometry (TOF/TOF) technique involving the use of a matrix-assisted laser desorption/ionization ion source that exhibits high precursor ion selectivity. An ion optical system with a 17 m spiral ion trajectory was used in the first time-of-flight mass spectrometer. High precursor ion selectivity was achieved by realizing a 15 m flight path, which is considerably longer than that of the conventional MALDI-TOF/TOF before the precursor ion selection by an ion gate; monoisotopic ions could be selected properly up to m/z 2500. Furthermore, the first time-of-flight mass spectrometer was composed of electrostatic sectors and could eliminate post-source decay (PSD) ions. Precursor ions with 20 keV kinetic energy were selected and injected into a collision cell, leading to the generation of fragment ions by high-energy collision-induced dissociation (HE-CID). The optimized second time-of-flight mass spectrometer included a post-acceleration region and an offset parabolic reflectron to record product ion spectra in the entire mass range. Our system could generate a simple HE-CID product ion spectrum because each fragment pathway could be observed as a single peak by the selection of monoisotopic ions of all precursor ions and HE-CID fragment pathways could be predominantly observed by the PSD ion elimination.     

Decomposition of Organometallic Complexes in the Mass Spectrometer

The reliable interpretation of mass spectra for the determination of molecular constitutions requires systematic studies on the fragmentation behavior of classes of compounds, since the large number of kinetic and energy parameters that determine the decomposition of excited polyatomic ions makes ab-initio predictions of spectra almost impossible. In this progress report, a number of general rules for the decomposition of organometallic complexes upon electron impact are discussed; a classification into decomposition types is also presented, and is illustrated by selected examples.     

On the Nature of Mass Spectrometer Analyzer Contamination

Sample throughput in electrospray ionization mass spectrometry (ESI-MS) is limited by the need for frequent ion path cleaning to remove accumulated debris that can lead to charging and general performance degradation. Contamination of ion optics within the vacuum system is particularly problematic as routine cleaning requires additional time for cycling the vacuum pumps. Differential mobility spectrometry (DMS) can select targeted ion species for transmission, thereby reducing the total number of charged particles entering the vacuum system. In this work, we characterize the nature of instrument contamination, describe efforts to improve mass spectrometer robustness by applying DMS prefiltering to reduce contamination of the vacuum ion optics, and demonstrate the capability of DMS to extend the interval between mass spectrometer cleaning. In addition, we introduce a new approach to effectively detect large charged particles formed during the electrospray ionization (ESI) process.

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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.     

气相色谱矩形离子阱质谱联用仪的设计与性能

气相色谱离子阱质谱联用仪(GC-ITMS)广泛地应用于药物分析、环境分析、农药检测和食品分析、有机化学品分析、毒品分析以及医学和生物分析等领域。离子阱质谱作为色谱的检测器,决定了色质联用仪的分析性能,包括检出限、分辨率。离子阱质量分析器从传统的双曲型3D离子阱发展到2D线性离子阱,质量歧视效应得到了极大的改善,灵敏度得到了提高。矩形离子阱作为线性离子阱,结构简单,加工和装配容易,因此应用到GCMS系统中将具有非常大的优势。介绍了矩形离子阱质谱仪的设计方案、仪器整机的性能测试、质量分辨和质量歧视效应分析,与Agilent6890组成GCMS联用仪,对实际样品进行了分析。     

Modification of Reflectron Time-of-Flight Mass Spectrometer for Photodissociation of Mass-Selected Cluster lons

We introduce a modification of reflectron time-of-flight mass spectrometer for laser photodissociation of mass-selected ions. In our apparatus, the ions of interests were selected by a mass gate near the first space focus point and decelerated right after the mass gate, were then crossed by a laser beam for dissociation. The daughter ions and surviving parent ions were re-accelerated and analyzed by the reflectron time-of-flight mass spectrometer. Compared to the designs reported by other research groups, our selection-deceleration-dissociation-reacceleration approach has better daughter-parent-ions-separation, easier laser timing, and better overlapping between the ion beam and laser beam. We also conducted detailed cal- culations on the parent ion and daughter ion flight times, and provided a simplified formula for the calibration of daughter ion mass.     

便携式飞行时间质谱仪用于室内甲苯、二甲苯污染快速溯源分析

采用自行研制的高时间分辨便携式飞行时间质谱(Portable time-of-flight mass spectrometry,P-TOFMS),基于网格布点检测法,在污染和通风自净后的条件下,以高暴露风险的甲苯、二甲苯作为VOCs代表物质,实时、在线监测1394 m2室内空气中的甲苯、二甲苯的浓度分布,并根据高时间分辨数据对污染源进行快速解析.结果表明,1.5h内即可完成室内40个采样点的全部分析工作;污染条件下室内甲苯和二甲苯的最高浓度为2633和223 μg/m3;自然通风24h后,浓度分别降低至113和173 μg/m3;2个模拟污染源及1个背景污染源均被准确识别.P-TOF-MS技术在家居、车间等室内空气VOCs污染源快速识别方面具有广阔的应用前景.     

聚氧乙烯醚的APCI+质谱分析

聚氧乙烯醚类表面活性剂在润滑油中起着乳化或抗乳化作用,许多乳化剂和抗乳化剂含有聚氧乙烯醚组分结构.该类物质的分子通式为:R-(CH2CH2O)nH,其中R可以是醇基、羧酸基或烷基酚基等等,是亲油基团,n是环氧乙烷的聚合度.这类物质是由高级醇、高级脂肪酸或长链烷基酚与环氧乙烷反应而制得的.运用APCI+源能很好的分析该类化合物.本文仅对不含R基的聚环氧乙烯醚[H(CH2CH2O)H]的分析作以介绍.     

电喷雾/光电离双源型小型离子阱质谱仪的研制

构建了一套电喷雾/紫外灯双电离源离子阱质谱仪系统,用于气体和液体样品的快速检测.仪器采用非连续大气压进样技术,通过夹管阀装置来同时完成电喷雾离子和中性气态样品的采集和传输.所配备的两种电离源适合不同的分析对象,在应用上具有一定的互补性,其中电喷雾源用于溶液中极性化合物的电离,而紫外电离源主要用于分析气态有机物.本研究选择了苯甲醚、甲苯、2,4-二甲基苯胺、精氨酸、利血平和阿斯巴甜等不同类型的样品,测试了仪器在使用不同电离模式下的工作性能.结果表明,电喷雾源和紫外光电离源可用于不同类型样品的电离,在分析2,4-二甲基苯胺时还能分别生成不同类型的分子离子.两种电离源在工作时互不干扰,既能单独使用,也能同时开启,可根据检测需求随意切换工作模式,获得更全面的样品成分信息.双离子源设计是扩展小型质谱仪应用范围的一种有效途径,这种方案不会明显增加仪器的体积,却能提供更多样化的分析功能,满足对不同类型样品的检测需求.     

研究级激光微探针飞行时间质谱仪及其应用

本文介绍了自行研制的激光微探针飞行时间质谱仪，阐述了该仪器的基本原理、结构特点、研究功能及其所达到的参量。该仪器是一台具有高分辩率、高灵敏度、研究功能强并兼具常规分析所需的简便、快捷的现代大型分析仪器。文章还介绍了该仪器的应用实例，如可作几万道尔顿以上的大分子物质分析，大分子蛋白质混合物的分析，有机化合物特别是难挥发和热不稳定有机物的分析，少至几十埃薄膜，如Ｃ６０等薄膜材料成分分析，负离子分析，以     

Chemical Sensors for Electronic Nose Systems

Chemical sensors have been widely used for the analysis of volatile organic compounds. Employing chemical sensors in an array format with pattern recognition provides a higher degree of selectivity and reversibility leading to an extensive range of applications. When such systems are used for odour analysis they are termed electronic noses. Application of electronic noses ranges from the food industry, medical industry to environmental monitoring and process control. Many types of different gas sensors have been employed in the array. These include conducting polymers, metal oxide semiconductors, piezoelectric, optical fluorescence and amperometric gas sensors The transducer principle of these sensors is varied and is discussed in detail within this review. Examples of the current trends in sensor array technology as well as the applications to which the sensor-based noses have been applied are also discussed.