甘油快原子轰击质谱的量子化学研究

用标准MNDO方法优化了甘油快原子轰击正离子谱中的主要离子构型,计算了生成热、质子化能以及亚稳断裂的活化势垒,研究了质子化甘油二步脱水反应的机理,并指出脱水产物C_3H_5O~+离子存在2种不同的构型。     

松三糖衍生物的快原子轰击质谱分析

1引言快原子轰击质谱在糖化学领域有广泛的应用,但涉及松三糖的研究却未见报道.松三糖是一种非还原性糖,是具有独特药用价值刺糖的主要成分?我们在研究松三糖羟基反应活性与结构的关系时,制备得到了一系列未见文献报道的松三糖衍生物,在用快原子轰击质谱(MS-FAB)研究它们的结构时.发现其中两个同为十-0-乙酰基松三糖的样品的裂解碎片有明显的差异,进一步研究发现它们是一对位置异构体,证实它们的差别在于其游离羟基分别位于果糖环的C-4位和C-6位?2实验邪分二.且仪器和实验条件ZAB-HS质谱仪门G公司),扫描范围2000p-200p,扫描速度20sjd,…     

金属盐在某些底物中的快原子轰击质谱

本文通过研究一系列盐类化合物在底物三乙醇胺和甘油醚中的快原子轰击质谱,总结出它们的加合阳离子系列,并从快原子轰击质谱的离化机理和亚稳跃迁结果探讨了这些离子的来源。     

寡肽的快原子轰击和碰撞活化质谱法分析

快原子轰击(FAB)软电离技术与碰撞活化(CA)技术联合用于寡肽中氨基酸顺序分析。在FAB质谱中出现明显的准分子离子峰(M H)~ 和(M Na)~ ,但碎片离子峰较微弱。然而在(M H)~ 离子的CA谱中有着明显的结构特征碎片离子峰,从而可明确地提供分子中氨基酸顺序的信息。这一技术可成为分析毫微摩尔寡肽氨基酸顺序的简便方法。曾以两个寡肽谷胱甘肽和五肽胃泌素作为例子研究了这一技术的应用。     

α—氨基酸的快原子轰击质谱

本文研究了１８种α－氨基酸的快原子轰击质谱，发现添加三氟乙酸溶液能显著提高灵敏度，改善谱图。特征碎片主要有中性丢失ＣＯ２Ｈ２，Ｈ２Ｏ，ＮＨ３的离子以及Ｒ＾＋离子。侧链的性质决定了碎片的产生和离子的强弱。     

含酯糖链皂甙的负离子快原子轰击质谱分析

本实验用负离子快原子轰击(FAB)法测定了8个含酯糖链的双糖链皂甙样品,给出了明显的脱质子分子离子峰,由碎片离子峰可推测糖基的连接顺序;不仅对难挥发、热不稳定和极性大的样品可直接进样分析,而且对在酯糖链皂甙中出现以酯裂解为基峰的碎片,还可初步确定糖链在甙元上的连接位置。     

快原子轰击质谱的非线性拟合法定量分析取代基海因

采用快原子轰击质谱法，在有底物甘油的条件下，测定f-5，5-二甲基海因，5-甲基-5-乙基海因的准分子离子峰[M＋H]^＋的质量色谱图，通过对其曲线拟合，发现它们的强度随采集时间呈指数衰减规律，并且，二者初始峰强的比值与仅与二者的浓度有关。当选定一个作为内标，则可对另一个定量分析。实验选择5-甲基-5-乙基海因作为内标，对5，5-二甲基海因定量分析。测得标准曲线方程为y=-0．0204＋0．154x（R=0．9921），线性范围在1～25μg之间，RSD为3．0％。     

Determination of the stability constants of macrocyclic ligand-alkali cation complexes by fast atom bombardment mass spectrometry

Quantitative studies of the complexation of the macrocylic ligands, 18 crown 6 (18C6,1) and cyclogentiotetraose peracetate (CGD4Ac,2), with alkali cations, have been investigated by fast atom bombardment mass spectrometry (f.a.b.m.s.). Complexation curves of 18C6 with Na⁺, K⁺, Rb⁺ and Cs⁺ in glycerol, and of CGD4Ac with Cs⁺ in PEG 200, were obtained by plotting the complex peak intensity against the alkali cation concentration. From these curves we describe a method to calculate the stability constant for an alkali cation-macroyclic ligand complex. There is a good agreement between stability constants obtained either by f.a.b.m.s. or calorimetric techniques for 18C6-alkali cation complexes. These results suggest that the f.a.b. technique can be used to study complex formation and determine the stability constant.     

Optimization of fast atom bombardment (FAB) mass spectra of arsenobetaine and arsenocholine

Optimized FAB mass spectra of arsenobetaine and arsenocholine may be obtained when the matrices glycerol and thioglycerol are used.     

Characterization of silicate monomer with sodium,calcium and strontium but not with lithium and magnesium ions by fast atom bombardment mass spectrometry

Fast atom bombardment mass spectrometry (FABMS) was applied to the direct detection of silica species dissolved in LiCl, NaCl, MgCl(2), CaCl(2) and SrCl(2) solutions in order to investigate its dissolution process in solution. Several species of dissolved silicate complexes in the solution were directly detected by FABMS. The peak intensities of [SiO(2)(OH)(2)Na](-), [SiO(3)(OH)Ca](-) and [SiO(3)(OH)Sr](-) increased with increasing concentrations of NaCl, CaCl(2) and SrCl(2), whereas the peak intensities of [SiO(2)(OH)(2)Li](-) and [SiO(3)(OH)Mg](-) did not increase with increasing concentrations of LiCl and MgCl(2). These results indicte that silicate and cation bind in the solution not after but before ionization. The isotope pattern of Sr(2+) confirmed the existence of the silicate-Sr complex not only with increase of the concentration of silica but also the mass numbers of Sr. The silicate complexes formed with Na(+), Ca(2+) and Sr(2+) showed high stability in chloride solution. This is in good accordance with the fact that Na(+), Ca(2+) and Sr(2+) accelerate the dissolution of silica to form complexes during solution equilibrium. Considering that the stability constant was examined and reported in other papers, this new findings that Mg(2+) does not form a complex with silicic acid (Si(OH)(4)) is very important.     

Assessment of metastable atom bombardment (MAB) ionization mass spectrometry for the fast determination of heterocyclic aromatic amines in cooked meat

An investigation of metastable atom bombardment (MAB) ionization mass spectrometry for the fast characterization of mutagenic/carcinogenic heterocyclic aromatic amines (HAAs) formed during heating processes of meats is presented. The aim of our study was to use the selective ionization of MAB to develop a detection method for HAAs in non-purified meat extracts, thus avoiding purification and concentration steps and reducing analysis time. Sample introduction into the MAB ion source was achieved by pyrolysis, allowing the direct and fast insertion of complex food extracts into the mass spectrometer. Analysis conditions were optimized on standard HAAs by using different ionization gases for the MAB process. Metastable nitrogen was selected as the best MAB gas for the analysis of HAAs. Ionization selectivity is shown by the detection of heterocyclic amines in non-purified chicken meat extracts spiked with HAAs. A quantitative approach is also presented by using pyrograms as chromatograms for quantification purposes. HAAs determination using Py-MAB-ToF was finally performed on cooked chicken breast extracts and compared to an LC-APCI-MS/MS method. Although Py-MAB-ToF sensitivity remains to be improved in the present state of development of our prototype device, only 2 h from the cooking were required to obtain quantitative results in good agreement with HAAs concentrations measured by LC-MS/MS in 36 h. Figure Experimental set-up for pyrolysis-MAB-ToF mass spectrometry experiments.     

Liquid chromatography/fast-atom-bombardement mass spectrometry of nonionic detergents

Summary Microcolumn liquid chromatography (LC) combined with fast-atom-bombardment mass spectrometry (FABMS) was applied to the analysis of nonionic detergents. The porous silver filter attached to the top of the capillary fused-silica tubing worked as the interface for coupling of micro LC and FABMS.     

Evaluation of thin layer chromatography—Fast atom bombardment mass spectrometry: Application to the determination of midazolam intoxication by use of 3-glycidoxypropyl-treated thin layer chromatographic plates

Summary The effectiveness of 3-glycidoxypropyl-treated thin layer chromatographic plates in the determination of midazolam intoxication has been studied by thin layer chromatography/fast atom bombardment mass spectrometry. Silica plates treated with 3-glycidoxypropyldimethylethoxysilane were used for the measurement of their physical composition and for chemical analysis. From elemental carbon analysis data, the maximum number of bonded 3-glycidoxypropyl surface groups per gram was calculated to be 0.417×10²¹. Midazolam in human serum from patients suffering from intoxication could be separated on a 3-glycidoxypropyl-treated thin layer chromatographic plate with chloroform as eluent. After applying the technique of diffused spot condensation on the 3-glycidoxypropyl-treated thin layer chromatographic plate, the established thin layer chromatography/fast atom bombardment mass spectrometry method was used for the identification of midazolam intoxication, and improved the detection limit for midazolam in the serum of an intoxication patient by 30 times.     

Direct microanalysis by negative ion fast atom bombardment mass spectrometry

In negative ion fast atom bombardment (FAB) mass spectrometry, the use of a liquid matrix comprised of 15-crown-5—glycerol (1:10, v/v) enabled the molecular weight determination of small amounts of non-volatile acidic molecules. This ionization process could result in detection limits of less than one-fifth of those obtained using only glycerol as matrix. The function of the matrix as a proton acceptor is emphasized.     

离子色谱-串联质谱法检测茶叶中的高氯酸盐

建立了离子色谱-串联质谱检测茶叶中高氯酸盐的分析方法。选用高容量、强亲水性的IonPac AS20阴离子交换柱（2 mm）进行分离,以淋洗液自动发生器在线产生的70 mmol/L氢氧化钾为淋洗液等浓度淋洗,TSQ Quantiva三重四极杆质谱仪作检测器,采用电喷雾电离源负离子（ESI^-）模式、多反应监测（MRM）模式进行分析,内标法定量。结果表明,高氯酸盐在0.02~10.0 μg/L范围内线性关系良好,相关系数（r）为0.9991,定量限为2 μg/kg。运用该方法测定5种茶叶中的高氯酸盐,加标回收率为87.3%~112.2%。该方法具有操作简单、专属性强、灵敏度高等优点,可满足茶叶中高氯酸盐的检测要求。     

Chemical reactions in fast atom bombardment mass spectrometry

Examples of various chemical reactions occurring in the matrix or in the selvedge region in fast atom bombardment (FAB) mass spectrometry are discussed. These are categorized as oxidations and reductions; substitutions; clusterings and additions; and sample decomposition or transformation. Some reactions observed showed significant time behaviour and in one case it was possible to determine rate constants. These data suggest that chemical reactions can be accelerated significantly by fast atom bombardment.