Fragment ion formation of quaternary ammonium salts under fast atom bombardment and field desorption collisionally activated dissociation conditions

Comparing fast atom bombardment and field desorption collisionally activated dissociation mass spectra of tetrabutyl ammonium salts it becomes evident that under fast atom bombardment conditions, besides desorption of intact salt cations, the ionization of intact salt molecules must be assumed. Alkyl ions formed under fast atom bombardment and not under field desorption collisionally activated dissociation conditions are ionization products of tetraalkyl ammonium salt molecules. Radical cations are produced by both techniques.     

An overview of LC–MS interfacing systems with selected applications

Advantages and limitations are described for the different LC–MS interfacing systems (moving belt; direct liquid introduction; thermospray; atmospheric pressure ionization with heated pneumatic nebulizer, electrospray, or high flow ion spray; particle beam; and continuous flow fast atom bombardment). Some comments are also made about interfacing capillary zone electrophoresis (CZE). The peculiarities of the various interfaces are described, as are liquid chromatographic requirements prior to mass spectrometry using the different ionization techniques. Selected biological and environmental applications are given.     

Analysis of xanthates by negative-ion fast atom bombardment mass spectrometry

A new technique using negative-ion fast atom bombardment mass spectrometry for the analysis of xanthates and related compounds is described. Electron impact and positive-ion fast atom bombardment mass spectrometry produced no structurally related fragment ions or observable molecular ions at the expected m/z values. It was demonstrated that negative-ion fast atom bombardment ionization was the most suitable method of ionization for structure elucidation studies for the compounds described.     

Mass spectral determination of long-chain quaternary amines in mixtures

The analytical utility of several ionization techniques, which are known for their abilities to produce molecular ions of non-volatile/thermally labile compounds, is compared for the determination of the composition of quaternary ammonium salt mixtures derived from beef tallow. The ionization techniques include direct-exposure chemical ionization, field desorption, and fast atom bombardment. While all three techniques produce molecular cations from the salts, fast atom bombardment produces these in greatest relative abundance. Both fast atom bombardment and direct-exposure chemical ionization can be used for characterization of the composition of chain lengths in the mixture. Fast atom bombardment also produces different fragmentation/decomposition ions (imminium ions) than direct-exposure chemical ionization (protonated tertiary amines).     

Direct coupling of micro high-performance liquid chromatography with fast atom bombardment mass spectrometry. II. Application to gradient elution of bile acids

A new system without a moving belt has been developed for direct coupling of micro high-performance liquid chromatography with fast atom (xenon or argon) bombardment mass spectrometry. The structure of the interface was basically the same as used previously, but the mass spectrometer was modified by adding both a liquid nitrogen trap between the ion source housing and the diffusion pump, and a position adjuster for the interface. Stable ionization of the solute in a glycerol matrix is achieved at flow-rates below 2 microliter/min. The system was applied to the analysis of bile acids by gradient elution chromatography. Steady baselines were observed in the mass chromatograms.     

Structure determination of a cyclic tetrapeptide : tentoxine by mass spectrometry using fast atom bombardment for ionization

The molecular mass and the sequence of tentoxine, a cyclic tetrapeptide, are determined by the mass spectrum of this compound which was obtained by a mass spectrometer using the fast atom bombardment for ionization.     

Reduction of methylene blue during the ionization process

Methylene blue is readily reduced during the process of ionization in methods as diverse as electron ionization, direct exposure probe electron ionization, direct exposure probe chemical ionization, solid sample secondary ion mass spectrometry, liquid sample secondary ion mass spectrometry and fast atom bombardment mass spectrometry. The reduction of methylene blue need not initially involve the abstraction of hydrogen from the solvent present in the latter two methods.     

Hydride abstraction in fast atom bombardment

Under fast atom bombardment conditions, compounds having long alkyl chains may exhibit [M ? H]⁺ as the major quasimolecular ion species, which can lead to incorrect assignment of molecular masses. It is shown that for a long-chain ether the loss of the hydride occurs from the hydrocarbon chain remote from the oxygen. This effect may yield information concerning ionization mechanisms in fast atom bombardment/mass spectrometry.     

质谱技术在糖类结构分析中的应用

综述了电子轰击、化学电离、快原子轰击、电喷雾离子化、基质辅助激光解吸、串联质谱等质谱技术在糖类结构分析中的应用。引用文献共53篇。     

The fast atom bombardment mass spectra of glucosinolates and glucosinolate mixtures

The behaviour of glucosinolates and desulphoglucosinolates under fast atom bombardment conditions has been investigated. Relatively little fragmentation was noted in the mass spectra of these compounds. The positive ion fast atom bombardment mass spectra of glucosinolates exhibited abundant cationized and protonated molecula ions, thus complementing the previously reported electron impact and chemical ionization mass spectra of these compounds. Desulphoglucosinolates yield only the protonated molecular ion. Under negative ion conditions the spectra of glucosinolates were dominated by the molecular anion and this has been used as a means of analysing a crude plant extract containing a complex mixture of glucosinolates.     

Field desorption mass spectrometry,fast atom bombardment mass spectrometry and fast atom bombardment tandem mass spectrometry of echinacoside,the main caffeoyl-glycoside from Echinacea angustifolia roots (Asteraceae)

The mass spectral fragmentation of echinacoside, a pharmacologically active caffeoyl-glycoside isolated from Echinacea angustifolia roots, has been investigated using different soft-ionization techniques, field desorption and fast atom bombardment (positive and negative ions) mass Spectrometry. Both ionization modes are successful in molecular mass determination and furnish approximately equivalent structural information. A fast atom bombardment tandem mass spectrometry approach (negative ions) was developed for the study of the fragmentation pathways and for the detection of echinacoside in crude plant extracts. The results demonstrate the usefulness of this technique for the rapid search of this important caffeoyl-glucoside directly in natural complex matrices.     

Alkali Metal Adduct Ions Technique in Combination with Fast Atom Bombardment/Tandem Mass Spectrometry in the Analysis of Oligoglycoside Mixtures

The combination of fast atom bombardment (FAB) with tandem mass spectrometry (MS/MS) has been shown to be a powerful tool for the characterization of oligoglycosides. Recent investigations of alkali metal attachment to oligoglycosides via ionization technique of Fast atom bombardment showed more possibilities for this propose^[1,2].     

Comparative EI,CI and FAB Mass Spectrometry of Dialkyl and Monoalkyl 2-Chloroethylphosphonates

Abstract

Comparison is made between electron ionization (EI), methane, isobutane and ammonia chemical ionization (CI) and fast atom bombardment (FAB) mass spectrometry of phosphonates related to 2-chloroethylphosphonic acid     

Mass spectrometric investigation of some macrocyclic and macroacyclic compartmental schiff bases

The mass spectrometric behaviour of four macroacyclic and five macrocyclic Schiff bases using two ionization methods (electron impact and fast atom bombardment) was studied in detail with the aid of mass-analysed ion kinetic energy (MIKE) spectrometry. It was possible to propose a common electron impact-induced decomposition pattern for the acyclic compounds, whereas for the cyclic compounds, analysed by fast atom bombardment, peculiar fragmentation routes occurred, which were strongly dependent on the macrocyclic structure and on the different side-chains.     

Differentiation of diastereomeric chlorin derivatives by fast atom bombardment mass spectrometry

The stereochemistry of six pairs of diastereomeric chlorin derivatives was investigated by electron impact (EI), fast atom bombardment (FAB) and direct chemical ionization DCI mass spectrometry. It was demonstrated that FAB and EI mass spectrometry are convenient and rapid methods for distinguishing between diastereomeric chlorin derivatives due to their different fragmentation patterns.     

Contribution of mass spectrometric techniques to the structure elucidation of antibiotic GE2270A,a novel inhibitor of bacterial protein synthesis

GE2270A is a novel antibiotic active against Gram-positive bacteria and anaerobes. Its structure originates from a peptidic backbone, the amino acids of which have been modified to produce a macrocycle and a side-chain. It contains a heterocyclic chrornophonc system, a number of thiazoleamino acids and three unmodified natural amino acids. The structure [relative molecular mass (RMM) 1289] was determined using various spectroscopic techniques, of which fast atom bombardment mess spectrometry, gas chromatography/mass spectrometry, desorption chemical ionization mass spectrometry and fast atom bombardment tandem mass spectrometry played an important role. The mass spectrometric approach was applied to the intact molecule and to the various hydrolysis products, including the chromophoric part (RMM 634).     

草酸根·(1R, 2R-环己二胺)合铂(Ⅱ)的质谱和热分析研究

铂配合物是目前最为广泛使用的抗肿瘤药物。自１９６５年Ｒｏｓｅｎｂｅｒｇ等人发现顺铂具有强烈抑制大肠杆菌细胞分裂的作用后［１］,对抗癌药物的研究和开发已成为生物无机化学的重要领域之一［２－４］。迄今为止,现已有四个铂配合物获准临床使用,其中之一就是草酸根·（１Ｒ,２Ｒ一环己二胺）合铂（Ⅱ）,它是由四氯合铂酸钾与反式－１, ２环己二胺的光学异构体作用,然后与草酸反应而制得的。为了深入研究该药物的物理性质,我们采用几种质谱方法和热分析仪对该化合物的分解机制和热稳定性进行了研究,探讨了分解的可能途径。１…     

Negative-ion electrospray and fast atom bombardment mass spectrometry of esters of boron acids

It is shown that both electrospray and fast atom bombardment mass spectrometry provide excellent negative-ion mass spectra of the anionic esters of boric, boronic and borinic acids. For electrospray, contact of the esters with water causes some hydrolysis but, in most cases, spectra of the intact molecular anions are readily obtained. For fast atom bombardment, solvents that chelate with the boron esters must be avoided, Tetraethylene glycol diethyl ether, pentaethylene glycol dimethyl ether or hexaethylene glycol dimethyl ether are suitable solvents. Negative-ion electrospray mass spectra showed few, if any, fragment ions, whereas fast atom bombardment generally produced abundant M^? ions and several fragment ions of low abundance. It is shown that a simple reaction with dibenzene-borinic acid converts diols such as monoglycerides and monoalkyl glyceryl ethers into anionic borinate esters as a pre-ionization procedure for analysis by electrospray or fast atom bombardment mass spectrometry.     

草酸根·(1R, 2R-环己二胺)合铂(Ⅱ)的质谱和热分析研究

The mass spectrum of oxalato(1R, 2R-cyclohexanediamine ) Pt has been studied by electrospray ionization (ES), electronic ionization (EI) and fast atom bombardment (FAB) techniques, respectively.The possible mechanism of the fragmentation process is discussed.The complex has also been characterized with its TG-DTA spectra.     

Comparison of ‘soft ionization’ techniques with electron impact mass spectrometry for desoxinojirimycin and folic acid derivatives

Seven desoxinojirimycin and three folic acid derivatives were investigated using the soft ionization techniques of desorption chemical ionization (DCI), laser desorption (LAMMA), field desorption (FD), secondary ion mass spectrometry (SIMS) and fast atom bombardment (FAB). The mass spectra were compared with electron impact (EI) spectra and interpreted in terms of their suitability for analytical purposes.