Fast bombardment mass spectra

Proton nmr titration experiments of [26] and [27] with KPF6 in acetonitrile revealed that in solution both compounds form 1 1 intramolecular sandwich complexes with the potassium cation. A number of alkyl-, vinyl- and azo-linked bis(benzo-15-crown-5) ligands are well known to exhibit this mode of K+ coordination. In the case of [26], a solid-state potassium complex was isolated whose elemental analysis and fast-atom bombardment mass spectrum ([26] K+ = 1083 complex ion) was in agreement with 1 1 complex stoichiometry (Fig. 20). 

References are given for spectroscopic studies, other v,c-oi IR hen these studies are reported in the synthetic/structural reference no further reference number is given. MS, mass spectrum FABMS, fast atom bombardment mass spectrum VT, variable-temperature. 

Figure 7. Fast atom bombardment mass spectrum of indapamide.

Figure 4, Fast atom bombardment mass spectrum of the diglutathtone conjugate of phenylalanine mustard (jM).

FIGURE 9.9 Example of a partial negative-ion fast atom bombardment mass spectrum of the total solvent extract from a marine bacterium showing phospholipid molecular species. Abbreviations PE, phosphatidylethanolamine PG, phosphatidylglycerol. 

By passing a continuous flow of solvent (admixed with a matrix material) from an LC column to a target area on the end of a probe tip and then bombarding the target with fast atoms or ions, secondary positive or negative ions are ejected from the surface of the liquid. These ions are then extracted into the analyzer of a mass spectrometer for measurement of a mass spectrum. As mixture components emerge from the LC column, their mass spectra are obtained. 

The relevance of oxygen and sulfur isotopic patterns is nicely demonstrated by the cluster ion series in fast atom bombardment (FAB) spectra of concentrated sulfuric acid, where the comparatively large number of sulfur and oxygen atoms gives rise to distinct isotopic patterns in the mass spectrum (Chap. 9). 

The mass spectrum of TTX can directly be measured by fast atom bombardment- or secondary ion-mass spectrometry. In the former a JEOL JMS DX-300 mass spectrometer equipped with a JEOL JMA-3100 data system is used xenon provides the primary beam of atoms. Acceleration voltage of the primary ion is 3 kV. Scanning is repeated within a mass range of m/z 100 to 1000. 

The low-resolution mass spectrum of Indinavir sulfate was measured using fast atom bombardment mass spectrometry on a JEOL HXl lOA mass spectrometer set at a resolution of 5000. The sample was ionized from a 5 1 dithiothreitol dithioerythritol matrix using xenon as the FAB gas. The low-resolution mass spectrum [12] ofindinavir is shown in Figure 14, while the structures of the structurally significant fragment ions are illustrated in Figure 15. 

The heptapeptide ulicyclamide (15) and the octapeptide ulithiacyclamide (16) were the first representatives of a series of cyclic peptides to be isolated from Lissoclinum patella. Their structures were elucidated by interpretation of spectral data [44], A revised structure was later put forward for ulicyclamide (15) as a result of a detailed analysis of the fast atom bombardment (FAB) mass spectrum. The same paper reported the isolation of two more polar cyclic peptides and another, which was present as a minor component. These heptapeptides were called lissoclinamides 1-3 (17-19) [45]. An unidentified tunicate from the Great Barrier Reef contained ulithiacyclamide (16) and ascidiacyclamide (14) [46]. Two syntheses of ulithiacyclamide (16)... 

Figure F2.4.2 Positive ion fast atom bombardment (FAB-MS) mass spectrum of phytofluene isolated from blueberries. The base peak of mlz (mass-to-charge ratio) 542 corresponds to the molecular ion. Characteristic of FAB-MS, background signals are observed at every mlz value. The mass spectrum was obtained during continuous-flow FAB-MS LC/MS using a magnetic sector mass spectrometer. Although the 16-c/s isomer of phytofluene is shown, the FAB mass spectra of the all- trans and other cis isomers are indistinguishable.

Figure F4.5.1 Positive ion fast atom bombardment (FAB) with collision-induced dissociation (CID) tandem mass spectrum of pyropheophytin a isolated from spinach leaves. The FAB matrix was 3-nitrobenzyl alcohol.

Fast atom bombardment mass spectroscopy has proved to be most useful when applied to the characterization of heteronuclear gold cluster compounds containing hydride ligands (137,149,155). Characterization is aided by the observation that peaks are invariably present in the spectrum corresponding to ions that contain all of the hydride... 

General (PAF and lysoPAF). The basic objective here is to examine the spectrum of a PAF sample subjected to fast atom bombardment-mass spectrometry (FAB-MS). The predominant feature of the resulting spectrum is the formation of a protonated mass ion. In actual fact, there is some cleavage of the molecule, but it is not extensive. These ions can, however, be used for diagnostic purposes. 

Clay, K. L., Sterre, D. O., and Murphy, R. C. (1984) Quantitative analysis of platelet activating factor (AGEPC) by fast atom bombardment mass spectrometry, Bio-med. Mass Spectrum 11, 47-49. 

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