Fast Atom Bombardment Mass composites

The average DS as determined by these methods provides only the simplest characterization of these derivatives, and further analysis was necessary to characterize the mixture of SBE bands of different levels of substitution. Due to the presence of the anionic sulfonate substituent, it is possible to use capillary electrophoresis (23), to separate the SBE-CD substitution bands and to characterize the fingerprint of the composition (Fig. 10). Anion exchange chromatography (24) was utilized to isolate separate substitution bands (mono- to deca-derivatives) that were subsequently identified by NMR and fast atom bombardment mass spectroscopy (FAB-MS). 

Tryptic Maps of Relaxin and Relaxin B-chain. Digestion of the A-chain of human relaxin with trypsin can theoretically result in the release of five fragments that of the B-chain in the release of six fragments as illustrated in Table II. A typical tryptic map of relaxin B-chain is shown in Figure 2. The peptide was reduced and carboxymethylated with iodoacetic acid before enzymatic digestion. The peptide assignments were made after analysis of the peaks by amino acid hydrolysis for amino acid composition and confirmed by fast atom bombardment mass spectrometry (FAB-MS) as shown in Table IH... 

The ZnCl2 system has probably been studied in the most detail. Fast atom bombardment mass spectrometry (FAB MS) has been used to identify the species present. It was found that ZnCl3, Zn2Cl5 and Zn3Cl7 species are all present in the liquids. The relative proportions of anionic species depend on the ionic liquid composition. Lecocq et al. [108] used electrospray ionization to look at the various species present and found that in Lewis basic liquids x(ZnCl2) <0.5 ZnC -whereas the di- and tri-metallate species were more prevalent in Lewis acidic liquids. 

From a practical perspective the chlorozincate liquids are easier to make and handle than the corresponding chloroaluminates as they are less susceptible to hydrolysis. As with the aluminum-based liquids the electrochemistry is dominated by the complex anions present in the liquid, which depend upon the composition and the relative Lewis acidity. There is some evidence, however, that hydrolysis of zinc Lewis basic melts does occur as Hsiu et al. used fast atom bombardment mass spectroscopy (FAB MS) to show that some zinc species do contain oxygen [105]. 

Mass spectrometry is a standard spectroscopic technique for the characterisation of high molecular weight organic and inorganic compounds, but has until recently received little attention from the zeolite community. The surface composition of zeolites has been explored using fast atom bombardment mass spectrometry (FABMS)[66] and secondary ion mass spectrometry [67], but mass spectrometric analysis of the bulk composition of a zeolite or of adsorbed molecules has not until very recently been attempted. The practical difficulty is to vaporise the solid. Two different strategies have been proposed laser ablation and plasma desorption. 

A variety of mass spectrometric approaches have been used for determining the isotopic composition and concentration of trace elements in biological matrices. The more commonly used are thermal ionization-mass spectrometry (TI-MS) [5,8], inductively coupled plasma-mass spectrometry (ICP-MS) [7,9], fast atom bombardment-mass spectrometry (FAB-MS) [10-12], and gas chromatography-mass spectrometry (GC-MS) [4]. 

Yassin, A. F., Haggeni, B., Budzikiewicz, H., and Schaal, K. P. (1993). Fatty acid and polar lipid composition of the genus Amycolatopsis Application of fast atom bombardment-mass spectrometry of underivatized phospholipids. Int. J. Syst. Bacterial. 43 414-420. 

Figure 7 Fast atom bombardment mass spectra obtained in glycerol matrix for quantitation of free carnitine and carnitine esters in the urines of a patient with medium-chain acyl-CoA dehydrogenase deficiency (A) and a patient with propionic acidaemia (B). The identities and concentrations of the annotated ions are listed in Table 2. The composition of the ions has been confirmed by measurements...

Ionization and fragmentation of materials by a variety of means, principally by electron bombardment, or the softer techniques of chemical ionization, field ionization or fast atom bombardment. Analysis of the range of mass fragments produced. Elemental composition of non-volatile materials by application of an RF spark. 

If high-resolution measurements are performed in order to assign elemental compositions, internal mass calibration is almost always required. The calibration compound can be introduced from a second inlet system or be mixed with the analyte before the analysis. Mixing calibration compounds with the analyte requires some operational skills in order not to suppress the analyte by the reference or vice versa. Therefore, a separate inlet to introduce the calibration compound is advantageous. This can be achieved by introducing volatile standards such as PFK from a reference inlet system in electron ionization, by use of a dual-target probe in fast atom bombardment, or by use of a second sprayer in electrospray ionization. 

The assumption for Eq. (1) is that the ELSD peak area is directly proportional to mass. For compounds of widely varying structures, charges, or vapor pressure, or for varying mobile phase compositions (e.g., gradient HPLC), the ELSD response can vary markedly (16-22). Thus, Eq. (1) is limited in its applicability. Similarly, mass spectral (MS) detectors are universal, but the response per unit weight depends greatly on the ionization type (e.g., electrospray, fast-atom bombardment, etc.) and on the ionization efficiency of the analyte. Refractive index is another universal detector, but it too suffers from variability in response depending on the mobile phase... 

A number of recent investigations have shown that mass spectrometry (MS) is a rapid and effective method for the identification of triacylglycerol species of milk fat that are compositionally different (Myher et al., 1988, 1993 Laakso and Kallio, 1993 Spanos et al., 1995 Laakso and Manninen, 1997 Mottram and Evershed, 2001 Kalo et al., 2004). In fact, a range of mass spectral techniques, such as electron ionization, fast atom bombardment, chemical ionization, atmospheric pressure chemical ionization and electrospray MS, have been used to study triacylglycerols. The later three are soft ionizing techniques, which retain substantial amounts of the molecular ion, rather than fragmenting the molecule into a number of parts. These methods have allowed the determination of... 

The composition of most FeD3(BR)2 complexes was confirmed by their electron impact (El), plasma desorption (PD), and fast atom bombardment (FAB) mass spectra. The molecular ion peaks were the most intense and corresponded to the theoretically calculated isotope peak series. 

We report on the further physical and chemical characterization of the new forms of molecular carbon, C ) and C70. Our results demonstrate a high yield of production (14%) under optimized conditions and reveal only and C70 in measurable quantity, in an 8S IS ratio. These two new molecular forms of carbon can be completely separated in analytical amounts by column chromatography on alumina. Comparison among mass spectra obtained by the electron impact, laser desorption, and fast atom bombardment (FAB) methods allows a clear assessment of the composition of the mixed and pure samples, and of the fragmentation and double ionization patterns of the molecules. In addition, spectroscopic analyses are reported for the crude mixture by C NMR and by IR spectroscopy in KBr pellet, and for pure C o and C70 in solution by UV-vis spectroscopy. 

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