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质子转移反应质谱用于痕量挥发性有机化合物的在线分析 总被引:2,自引:0,他引:2
质子转移反应质谱(PTR-MS)是一种化学电离源质谱技术,专门用于痕量挥发性有机化合物(VOCs)实时在线检测.此技术利用H3O-作化学电离源试剂离子与作为质子接受体的VOCs发生质子转移反应.大气中的O2,N1,CO2等主要成分由于其质子亲和势低于H2O,而不与H3O发生质子转移反应,因此可在大气环境下检测痕量VOC... 相似文献
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食品中化学性有害物是导致食品安全问题的重要原因,质谱是对食品中化学性有害物进行定性定量分析的有效方法。该文按照化合物结构类别,综述了食品中重要化学性有害物的质谱软电离裂解机理,包括农药、兽药、真菌毒素,以及其他化学污染物。对于每类化合物,重点综述化合物质谱裂解产生的特征碎片、中性丢失等,以及这些质谱软电离裂解机理在食品中化学性有害物筛查及发现中的应用。研究化合物的质谱裂解机理可以帮助研究者对化合物进行结构解析和结构确证,为食品中同类结构新型化学性有害物的发掘提供理论依据。 相似文献
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电喷雾电离质谱在富勒烯化学中的应用进展 总被引:2,自引:0,他引:2
电喷才电离质谱(ESI-MS)是本世纪发展的一种非常重要的质谱,具有软电离、无碎片的特点,可用于分析检测非挥发性的,极性的、热不稳定的化合物,在富勒烯化学研究中起了重要作用。本文对ESI-MS在富勒烯化学中的应用进展作一概要评述。 相似文献
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电喷雾电离质谱在化学中应用新进展 总被引:11,自引:0,他引:11
电喷雾电离质谱(ESI-MS)是本世纪发展的非常重要的质谱,具有无碎片的特点,可分析检测非挥发性的、极性的、热不稳定的化合物。评述了ESI-MS在富勒烯化学、无机配合物、簇合物、有机化学反应,金属有机化合物及超分子化学中的应用进展。 相似文献
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Gas phase protonolysis reactions of a wide variety of N-nitrosamines have been studied utilizing methane chemical ionization mass spectrometry (CIMS). N-Nitrosamines are protonated at either the N or O atoms of the N-nitroso triad (NNO) leading to aminium radicals, nitrenium ions, ammonium ions, carbenium ions and various elimination reaction. A structure-CIMS reactivity relationship of N-nitrosamines is presented. 相似文献
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The rate constants and product ion branching ratios have been measured in a selected ion flow tube (SIFT) at 298 K for a variety of positive and negative ions reacting with 2-chloroethyl ethyl sulfide (2-CEES), a surrogate for mustard gas (HD). This series of experiments is designed to elucidate ion-molecule reactions that have large rate constants and produce unique product ions to guide the development of chemical ionization mass spectrometry (CIMS) detection methods for the chemical weapon agent using the surrogate instead. The negative ions typically used in CIMS instruments are essentially unreactive with 2-CEES, that is, SF 6 (-), SF 4 (-), CF 3O (-), and CO 3 (-). A few negative ions such as NO 2 (-) and NO 3 (-) undergo three-body association to give a unique product ion, but the bimolecular rate constants are small in the SIFT. Positive ions typically react at the collisional limit, primarily by charge and proton transfer, some of which is dissociative. For ions with high proton binding energies, association with 2-CEES has also been observed. Many of these reactions produced ions with the 2-CEES intact, including the parent cation, the protonated cation, and clusters. G3(MP2) calculations of the thermochemical properties for 2-CEES and mustard have been performed, along with calculations of the structures for the observed product cations. Reacting a series of protonated neutral molecules with 2-CEES brackets the proton affinity (PA) to between 812 ((CH 3) 2CO) and 854 (NH 3) kJ mol (-1). G3(MP2) calculations give a PA for 2-CEES of 823 kJ mol (-1) and a PA for mustard of 796 kJ mol (-1), indicating that the present results for 2-CEES should be directly transferable to mustard to design a CIMS detection scheme. 相似文献
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Kovacik V Patoprsty V Petrus L Ovcharenko V Pihlaja K 《Journal of mass spectrometry : JMS》2000,35(5):634-638
O-Isopropylidene and O-benzylidene acetals of common 2, 6-anhydro-1-deoxy-1-nitroalditols (beta-D-glycopyranosylnitromethanes) derived from D-glucose, D-galactose and D-mannose were studied by chemical ionization mass spectrometry (CIMS) using methane, isobutane, ammonia or pyridine as reaction gas. Production of [M+H](+) adduct ions dominates in the case of methane or isobutane possessing proton affinity values PA = 552 or 683 kJ mol(-1), respectively. The collision-induced dissociation time-of-flight product ion spectra of [M+H](+) ions differ characteristically according the stereochemical arrangement of the pyranoid ring. These differences can be helpful when assigning stereochemical arrangements for the pyranoid ring. The dominant process in ammonia (PA = 853 kJ mol(-1)) CIMS for most of the compounds studied is the production of the cluster ions [M+NH(4)](+). The cluster [M+pyridineH](+) ions are observable only for substances possessing the O-benzylidene group (PA of pyridine = 924 kJ mol(-1)). Copyright 2000 John Wiley & Sons, Ltd. 相似文献
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《Analytical letters》2012,45(7-8):575-579
Abstract The chemical ionization mass spectra of fluorescamine and fluorescamine - amino acid derivatives have been studied using methane and ammonia as reagent gases. Major ions in the spectra are protonated molecular ions, adduct ions and ions formed by loss of an oxygen atom. Fluorescamine, 4-phenyl-spiro[furan-2(3H),1′-phthalan]3,3′-dione, is a powerful new fluorogenic reagent for assaying primary amines.1 and EI2 and EI3 mass spectrometric investigations of fluorescamine and its derivatives were carried out. Our present study reports the CI mass spectral analysis of fluorescamine and some of its amino acid derivatives. 相似文献
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The application of gas chromatography chemical ionization mass spectrometry to the determination of a variety of alkyl alkylphosphonates, phosphonofluoridates, phosphonothiolates and an amidophosphorocyanidate is described. Comparison is made between the electron ionization and chemical ionization mass spectrometry of these compounds. Chemical ionization mass spectrometry is shown to enhance the capability for identification, especially when a limited sample is available. Results indicate that methane is highly useful for obtaining protonated molecular ions and association ions (formed by the transfer of a reactant ion to a sample molecule) as well as meaningful fragment ions. Ionizing ethylene and isobutane gives protonated molecular ions as base peaks for all of the compounds studied, including those where a lower abundance of the [MH]+ ion is found via methane chemical ionization mass spectrometry. Ethylene is superior to isobutane on the basis of its effectiveness for serving as both a carrier and a reagent gas and gives better sensitivity. Although not an intrinsic part of this present study, analytical sensitivities in the subnanogram range were found. 相似文献
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This study examines the reagent gas pressure and ion source temperature dependence for dimethyl ether chemical ionization (DME CI) mass spectra recorded with an external source ion trap mass spectrometer (ITMS). Information for better controls of the reagent gas pressure in order to obtain fair CI spectra is provided. The origin of M+? ions observed in DME CIMS is discussed in detail. Furthermore, the ion source temperature effect on the DME CI is also investigated. 相似文献
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The methane and isobutane chemical ionization mass spectra of alicyclic substituted 2-aryl-1,3-dithianes were examined by gas chromatography mass spectrometry. The protonated molecular ion was found to be of low abundance in the methane spectra, while a protonated cyclic sulfide cation (m/z 107) appeared as the base peak. A protonated molecular ion was the base peak when isobutane was used as the reagent gas. Electron impact mass spectra displayed weak molecular ions and were characterized by the m/z 106 fragment. 相似文献
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Rimetz-Planchon J Dhooghe F Schoon N Vanhaecke F Amelynck C 《Rapid communications in mass spectrometry : RCM》2011,25(5):647-654
Existing on-line Chemical Ionization Mass Spectrometry (CIMS) techniques for quantification of atmospheric trace gases, such as Biogenic Volatile Organic Compounds (BVOCs), suffer from difficulty in discriminating between isomeric (and more generally isobaric) compounds. Selective detection of these compounds, however, is important because they can affect atmospheric chemistry in different ways, depending on their chemical structure. In this work, Flowing Afterglow Tandem Mass Spectrometry (FATMS) was used to investigate the feasibility of the selective detection of a series of monoterpenes, an oxygenated monoterpene (linalool) and a sesquiterpene (β-caryophyllene). Ions at m/z 137 from [H(3)O](+) chemical ionization of α-pinene, linalool and β-caryophyllene have been subjected to Collision-Induced Dissociation (CID) with Ar in the collision cell of a tandem mass spectrometer at center-of-mass energies ranging between 0 and 8 eV. Similar fragmentation patterns were obtained, demonstrating that this method is not suited for the selective detection of these compounds. However, CID of the ions at m/z 136 produced via [NO](+) chemical ionization of a series of monoterpenes has revealed promising results. Some tracer-product ions for individual compounds or groups of compounds were found, which can be considered as a step forward towards selective on-line monitoring of BVOCs with CIMS techniques. 相似文献
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The chemical ionisation mass spectra of a number of representative explosives have been obtained using hydrogen as reagent gas. Fragmentation modes of the protonated molecular ions tend to be simple although some rearrangements have been noted. Loss of a radical from an even electron parent ion has been observed. The use of ‘ghost spectra’ for confirmation of the molecular weight of the sample is stressed: these consist of ions of low abundance resulting from reactions between sample ions and sample molecules. Labelling studies were carried out using deuterium as reagent gas. 相似文献
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M. F. N. Duarte D. W. Hutchinson K. R. Jennings 《Journal of mass spectrometry : JMS》1985,20(7):476-478
Conditions have been established for the detection by chemical ionization mass spectrometry (CIMS) of compounds related to L -dopa (3-hydroxy-L -tyrosine) and L -tryptophan without derivatization. The least fragmentation of the parent ion occurs in positive ion CIMS when methylamine is used as reagent gas. The compounds can also be detected by negative ion CIMS using carbon tetrachloride as reagent gas. While the total ion current in the latter technique is lower than that obtained with positive ion CIMS, the background noise in the mass spectra of samples obtained from natural sources is greatly reduced. CIMS has been used to show the presence of aromatic amino acids in acid extracts of samples of two different classes of tumour without sample derivatization. 相似文献