Frank W. Crow

Triple analyzer mass spectrometry for high resolution MS/MS studies

Abstract A high resolution MS/MS instrument comprising electrostatic analyzer, magnetic sector, electrostatic analyzer (EBE) is described. Analytical applications of this instrument require high resolution mass selection, high dynamic range and good transmission for collision-induced decomposition (CID) fragments. Suitable experiments are reported as an evaluation of these requirements. It is found that CID spectra can be obtained for ion components separated at a mass resolution of 100 000. At lower resolving powers, a dynamic range of 100 000 for mixture constituents is demonstrated. Finally, a transmission of 4% for ion fragments produced in CID from methane is established.

Fast atom bombardment combined with tandem mass spectrometry for the determination of nucleosides

The positive and negative ion fast atom bombardment (FAB) mass spectra and fast atom bombardment collisionally activated decomposition (CAD) spectra of a series of nucleosides and two dinucleotides are reported. The nucleosides studied are substituted forms of guanosine, adenosine, nebularine, tubercidin, uridine, and related pyrimidines. The FAB and CAD data both contain similar information. The CAD spectra are found to provide some structural information not found in the FAB mass spectra. Tandem mass spectrometry also allows emphasis to be put on weak fragments which are either not observed in the FAB mass spectrum or are lost in the matrix ion signals.

The structure of the toxin from helminthosporium carbonum

Using Fast Atom Bombardment Mass Spectrometry and Mass Spectrometry/Mass Spectrometry, the structure of HC-toxin a metabolite of Helminthosporium carbonum, is postulated to be structure 3.

Fast atom bombardment and tandem mass spectrometry for structure determination of steroid and flavonoid glycosides

The combination of fast atom bombardment (FAB) and tandem mass spectrometry (MS-MS) was tested for its applicability to generate useful structural information for steroid and flavonoid glycosides. The following compounds were investigated: quercetin, myricitrin, apigetrin, fraxin, rutin, neohesperidin, hesperidin, naringin, apiin, cymarin, digoxin, digitoxin, xanthorhamnin, and frangulin. Upon FAB, the sample molecules are desorbed as (M + H)+, (M - H)-, or as (M + Na)+ or (M + K)+. Collisional activation of (M + H)+ or (M - H)- ions in the MS-MS experiment leads to sequential losses of glycoside moieties in a manner which permits the sequence of glycosides to be established. Some glycosides occur as mixtures of homologs. Proper interpretation of the MS-MS or collisional activation decomposition spectra often allows the homology to be located. In addition to the simple and highly selective fragmentations observed in this combined experiment, FAB and MS-MS also remove interference caused by the ubiquitous matrix ions which are desorbed by FAB.

Ribosyl-diphthamide: confirmation of structure by fast atom bombardment mass spectrometry.

Diphtheria toxin inactivates protein synthesis elongation factor 2 by attaching ADP-ribose to an unusual post-translational amino acid derivative, diphthamide, in the factor. Previously, we prepared ribosyl-diphthamide from the ADP-ribosyl-factor and proposed on the basis of NMR spectral analysis that it is 1-alpha-D-ribofuranosyl-2-[3-carboxyamido-3-(trimethylammonio++ +)propyl] histidine [N. J. Oppenheimer, and J.W. Bodley, (1981) J. Biol. Chem. 256, 8579-8581 and op. cit.]. Now, using fast atom bombardment mass spectrometry, the intact cation of ribosyl-diphthamide has been observed in the gas phase. The theoretical mass of the structure proposed for ribosyl-diphthamide uniquely agrees with the observed mass of the inact cation of the compound to within 2 ppm. Collisional activation decomposition mass spectral analysis provided additional structural confirmation. Thus, although the compound has not been synthesized, all available evidence appears uniquely consistent with the structure of ribosyl-diphthamide previously proposed.

Analysis of mixtures of ionic compounds using Fast Atom Bombardment and a triple analyzer mass spectrometer

Abstract The combination of fast atom bombardment (FAB) and mass spectrometry/mass spectrometry (MS/MS) has been applied to the analysis of cyclic peptides and anionic surfactants.