Liquid chromatography-electron ionization mass spectrometry: fields of application and evaluation of the performance of a Direct-EI interface

A comprehensive evaluation and a thorough discussion of the fields of possible applications of the Direct-EI interface are described in this review. Direct-EI allows the direct introduction of the effluent from a capillary HPLC column into the electron ionization (EI) ion source of a mass spectrometer. Thanks to the reduced liquid intake and an in-source nebulizer, the interfacing process occurs smoothly and entirely into the ion source. No intermediate interfacing mechanisms of any sort are interposed between the column and the mass spectrometer, thus circumventing any undesired sample loss and minimizing the effort for instrument modification. Theoretically, any GC-MS system can be converted into an LC-MS for EI amenable compounds. Several parameters, crucial for a successful integration of liquid chromatography and mass spectrometry, have been considered in the evaluation of the functioning of such an interface: limit of detection, linearity of response, reproducibility, and chromatographic compatibility. Different mobile phases, also containing non-volatile buffers, were taken into account, demonstrating an outstanding separation flexibility. The entire set of experiments was carried out at different flow rates and temperatures of the ion source. The interface behavior was also tested in real world applications, with mixtures of pesticides, hormones, nitro-PAH, and endocrine-disrupting compounds, allowing picogram level detection and the possibility to record library-matchable, readily interpretable electron ionization mass spectra, for prompt compound characterization and confirmation.     

2,3,5,6-四氯-4-甲磺酰基吡啶的离子阱质谱研究

采用电子轰击离子阱质谱对2,3,5,6四氯4甲磺酰基吡啶(TCMSP)的裂解规律进行了研究。发现其质谱特征除了磺酰基与吡啶环相连的CS键的断裂和CCl键的断裂,还有伴随着氢重排的OC键断裂。对m/z231的碎片离子进行了二级质谱研究,推断了该碎片的结构。     

Modification of an AEI/GEC MS9 High-Resolution Mass Spectrometer for Electron Impact/Chemical Ionization Studies

ABSTRACT

A double-focusing MS9 mass spectrometer has been modified to permit operation in both chemical ionization (CI) and electron impact (EI) modes. The modifications consist mainly of a closed ion chamber, a high capacity pumping system, a reactant gas inlet system, a new solid sample probe, and a source pressure measuring device. Changes have also been made in the electronic system and a new ion source power supply has been incorporated. The new ion source can be operated in the CI mode at pressures up to 1 Torr while the pressure in the analyzer is better than 10^?7 Torr. The new set-up has the ability to analyze solid, liquid, and gas samples in both CI and EI mode. It has also the ability to do GC/MS without a Separator.

The sensitivity in the CI mode is comparable to the sensitivity in the EI mode, and the maximum resolution obtained with the CI/EI source is similar to that obtained with the original EI source.     

二甲基二硫逐焦膦酸二甲酯合成样品中化合物的质谱特征、碎裂机理及其鉴定

为了掌握二甲基二硫逐焦膦酸二甲酯的质谱特征,开展了该化合物合成样品的气相色谱 质谱(GC/MS)和串联质谱(MS/MS)分析鉴定研究。利用GC/MS联用技术对混合物进行分析,得到10个组分的电子电离（EI）和化学电离（CI）全扫描质谱信息。根据CI谱图中的同位素比值,推测化合物可能的元素组成;通过EI谱图与数据库谱图比对,鉴定了其中6个组分的结构。然后,对二甲基二硫逐焦膦酸二甲酯和4个未知化合物采用MS/MS模式获得各自的裂解碎片,通过分析不同的裂解碎片,推测未知化合物可能的结构,并解释其可能的碎裂途径。实验共鉴定出合成样品中10个化合物,并总结了不同化合物的质谱特征,可为相关化合物的分析和鉴定提供参考。     

A homemade high-resolution orthogonal-injection time-of-flight mass spectrometer with a heated capillary inlet

We describe a homemade high-resolution orthogonal-injection time-of-flight (O-TOF) mass spectrometer combing a heated capillary inlet. The O-TOF uses a heated capillary tube combined with a radio-frequency only quadrupole (rf-only quadrupole) as an interface to help the ion transmission from the atmospheric pressure to the low-pressure regions. The principle, configuration of the O-TOF, and the performance of the instrument are introduced in this paper. With electrospray ion source, the performances of the mass resolution, the sensitivity, the mass range, and the mass accuracy are described. We also include our results obtained by coupling atmospheric pressure matrix-assisted laser deporption ionization with this instrument.     

气相色谱-质谱联用法测定沙纳唑的血药浓度

用气相色谱 -质谱联用法 ,选用甲硝唑为内标物 ,测定了肿瘤病人给药后血浆中沙纳唑的浓度 ,方法简便、准确。     

有机质谱学在厚朴酚与和厚朴酚结构确定中的应用

采用超临界CO₂ 提取方法对厚朴药材的化学物质进行提取，用毛细管气相色谱-质谱联用技术(GC/MS)对提取物进行分析。在厚朴酚与和厚朴酚的质谱中，其分子离子峰M^•+(m/z 266)均为基峰，主要碎片峰 m/z 237、184、165、91、77都相一致，而碎片峰 m/z 247是区别厚朴酚与和厚朴酚化学结构的典型质谱特征。     

美国白蛾性信息素中两主要成分的质谱研究

人工合成美国白蛾性信息素的两个主要成分即 (9z,1 2 z) -十八碳二烯醛 I及 (9z,1 2 z,1 5 z) -十八碳三烯醛 ,应用 GC/MS证实其结构。依照 EI谱分子裂解的主要特征碎片 ,讨论了两个分子的具体裂解途径     

气相色谱-质谱离子源内气体密度的数值分析

利用计算流体力学法,对气相色谱-质谱联用仪电子轰击离子源内的气体分布进行数值分析,计算进样毛细管插入离子源不同深度,以及毛细管不同孔径时离子源内气体的分布状态,并讨论毛细管插入深度以及毛细管孔径对离子源内气体分子密度分布的影响。结果表明,毛细管插入离子源特定深度时,离子源离子化区域密度最大。不同孔径的毛细管对离子源密度影响不大。本工作以气体场理论为基础,分析离子源内气体分布状况,为研究气体密度分布对离子源电离效率的影响提供分析方法。     

电子轰击源垂直加速式飞行时间质谱仪的研制

介绍了自制的电子轰击离子源（electron ionization, EI）垂直加速式飞行时间质谱仪（orthogonal acceleration time-of-flight mass spectrometer, Oa-TOF MS）的原理,结构以及初步的实验结果。搭建了电子轰击源垂直加速式飞行时间质谱仪,并得到室内空气成分谱图。结果表明,仪器分辨率优于2 000（full width at half maximum,FWHM）,质量精度优于4×10^-5,可以用于气体成分的快速定性分析。     

不同接口对高效液相色谱－质谱分析甾体激素的影响

本文采用传送带接口和热喷雾接口，以８种甾体激素的混合标样，就不同接口对ＬＣ／ＭＳ的影响进行了评价。     

大气压接口-单四极杆质谱仪的研制

本工作研制一种具有大气压接口的单四极杆质谱仪。该仪器具有三级真空系统,与大气相邻的第一级真空接口基于加热的不锈钢毛细管设计;在第二级真空腔中采用射频高压驱动的方式远距离传输离子;第三级腔体放置四极杆和电子倍增器分离和探测离子,使用自制的控制系统控制仪器。基于此仪器,实现了大气压下电喷雾离子源、介质阻挡放电离子源离子化样品的检测,通过第一级腔体中的源内碰撞诱导解离获得了样品的二级子离子,增强了单四极杆质谱仪的定性能力。该仪器结构简单、成本低,可用于液相色谱-质谱联用分析和原位分析。     

喹喔啉类化合物的质谱研究

本文报道了２，６－二取代、２，３－二取代喹喔啉类化合物的电子轰击质谱。根据高分辨质谱及联动扫描质谱揭     

电喷雾质谱法研究4种青蒿素类药物的质谱裂解特征

采用电喷雾-飞行时间质谱法(ESI-TOF MS)在正离子检测方式下,以注射泵直接进样的方式对4种青蒿素类药物进行碰撞诱导解离(CID)研究,获得各化合物的质谱碎片信息。以准分子离子[M+Na]⁺作为内标物,对碎片离子进行准确质量测定,确认这些碎片离子的元素组成,探讨该类化合物的质谱裂解途径。通过比较各化合物结构和质谱裂解途径的异同点,发现青蒿素类药物主要通过O-O及C-O键发生裂解,生成脱H₂O、CO、HCOOH和CH₃COOH的碎片离子,其中m/z 261和m/z 163为青蒿素类衍生物特有的碎片离子,这些特征将有助于青蒿素类化合物的结构解析。     

On-Line Thermogravimetry/Gas Chromatography/Mass Spectrometry

ABSTRACT

An on-line thermogravimetry/gas chromatography/mass spectrometry (TG/GC/MS) system has been constructed through additions to and appropriate modifications of commercially available instruments. The system employed a Du Pont 951 thermogravimetric analyzer coupled to a Hewlett-Packard 5890 gas chromatograph/5970 mass selective detector system. A nickel tube, inserted directly into the area immediately above the TG sample pan, acted as a transfer line. An adsorbent trap with a heater and a heated six-way valve was installed between the TG and the GC. The volatile compounds generated from selected materials in the TG were adsorbed by the trap. After the heating and purging process, the trap was rapidly heated and the volatile compounds in the trap were swept into the GC injector and were then analyzed by GC/MS. The on-line TG/GC/MS system was examined by using selected natural products. A number of volatile compounds were generated from the samples by TG, separated by GC and identified by MS. The stability, the weight loss, and the evolution of compounds from the materials could be analyzed and studied.     

用大气压电喷雾电离质谱对二硝化纤维素(PYX)的研究

用柱塞泵进样、大气压电喷雾电离方法对得不到分子离子的耐热炸药二硝化纤维素 (PYX)作了负离子质谱分析。通过改变毛细管出口 Cap Ex电压产生碰撞诱导裂解 (Collision-induced dissociation,CID) ,得到较多的化合物结构碎片离子。与电子轰击电离 (EI)源质谱图作了对比 ,确认了 8个特征碎片离子 ,得到比较满意的结果     

大气漂尘中多环芳烃的GC／MS研究

本文应用毛细管柱气相色谱／质谱联用技术（ＧＣ／ＭＳ）对大气漂法吉的多环芳烃分析研究。漂尘样采于玻璃纤维滤膜上，经ＣＨ２Ｃｌ２超声提取和凝胶硅胶柱二次分离后，由ＧＣ／ＭＳ测定，定性检出４６种多环芳烃，并对９种主要多环芳烃定量分析。     

青胶蒲公英化学成分鉴定及质谱裂解规律研究

采用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱（UHPLC-Q/Orbitrap HRMS）对青胶蒲公英中的化学成分进行快速分析鉴定。将青胶蒲公英的根、叶干燥粉碎,经超声/微波辅助萃取,采用Waters ACQUITY BEH C18色谱柱 (100 mm×2.1 mm×1.7 μm),以0.1%甲酸水溶液和乙腈为流动相进行梯度洗脱。洗脱液经大气压化学电离源（APCI）离子化后,采用全扫描-数据依赖型二级质谱扫描模式进行数据采集。将预处理后的数据与中药数据库及在线数据库等比对分析,包括一级精确质荷比、同位素峰分布以及二级质谱图匹配,共鉴定出164种化合物,包括黄酮类、香豆素类、萜类、有机酸类、生物碱类、木质素类等,同时对部分鉴定成分的质谱裂解规律进行推导,有助于黄酮类等化合物的结构解析,为青胶蒲公英中黄酮类等成分结构类似物的快速鉴定提供了重要的实验依据。     

液相色谱/离子阱质谱法检测不同食用植物油中的叔丁基对苯二酚(TBHQ)

本文采用液相色谱/离子阱质谱法(LC/ITMS)对食用植物油中的抗氧化剂叔丁基对苯二酚(TBHQ)进行定量检测。样品经萃取后,以甲醇-水(体积比50∶50)作为流动相,以C18作为分离柱,以电喷雾离子源作为接口,在负离子检测模式下进行一、二级质谱分析。二级质谱检测的线性范围为61.8~4 542.5μg/L(R2=0.999 9),最低检出限为48μg/L;10种食用植物油中TBHQ的回收率为(81.9±1.9)%~(109.6±4.6)%,RSD(n=10)≤5.3%。该法能快速、简便、准确地检测食用植物油中的抗氧化剂TBHQ。     

An All Glass-Lined,Open-Split,Solvent-Venting Interface for Gas Chrohatography-Micromave Induced Plasma Emission Spectroscopy (Gc-Mip)

ABSTRACT

An instrument is described that allows for the simple interfacing of packed glass column gas chromatography with microwave induced plasma emission spectroscopic detection (GC-MIP) for trace organic, organometallic, or inorganic type analyses. The final GC-MIP instrumentation is an all glass-lined system, with an open-split type interface between the end of the GC column and the plasma discharge tube of the MIP detector. This interface permits the rapid and efficient venting of the GC solvent front, together with an efficient transfer of the sample analytes from the GC column to the plasma discharge tube. The overall instrumentation is inexpensive, simple to construct, relatively easy to operate, thereby permitting the routine use of GC-MIP for a wide variety of metal/non-metal containing organic, inorganic, or organometallic species. True metal speciation is also possible via this instrumental approach.