R. Donald Sedgwick

Fast atom bombardment of solids (F.A.B.): a new ion source for mass spectrometry

A new method for obtaining high-quality mass spectra of molecules which previously were difficult or impossible to study by ionisation methods is described

Fast atom bombardment mass spectrometry (FABMS). A study of surface coverage effects in FABMS

A study of various surfactants using FABMS and surface tension measurements is described. A correlation between surface structure and FAB mass spectral response is reported with its possible significance in the ionisation mechanism.

Characterisation of an adrenal zona glomerulosa-stimulating component of posterior pituitary extract as bisacetyl-Ser1-α-MSH

Abstract HPLC fractionation of the posterior pituitary preparation, Pitressin, affords two major peaks of aldosterone stimulating activity. The second component has now been characterised as bisacetyl-Ser 1 -α-MSH using protein chemical and mass spectrometric techniques. Fast atom bombardment mass spectrometry of the biologically active substance yielded a protonated molecular ion at m m z 1706. Electron impact mass spectrometry of the N-terminal dipeptide isolated from a chymotryptic digest of the active peptide allowed the site of O-acetylation to be determined. Bioassays using rat adrenal glomerulosa cells showed that the activities of bisacetyl-Ser 1 -α-MSH and α-MSH are virtually identical.

Fast atom bombardment mass spectrometry of bovine insulin and other large peptides

The observation of protonated molecular species from bovine insulin and adrenocorticotropic hormone is reported, together with sequence information for melittin, obtained by fast atom bombardment mass spectrometry.

Synthesis and properties of Group 5B ligand analogues of o-phenylenebis(dimethylarsine), o-C6H4(EMe2)(E′Me2) where E, E′= P, N, As, or Sb

Lithium dimethylphosphide prepared from lithium and PMe2Ph in tetrahydrofuran reacts with o-dichlorobenzene to produce o-phenylenebis(dimethylphosphine). Similar reactions using the appropriate o-bromophenyl derivatives o-C6H4Br(Y)(Y = NMe2, AsMe2, or SbMe2) yield o-C6H4(PMe2)Y. o-Phenylenebis(dimethylstibine) is best prepared from (o-bromophenyl)dimethylstibine and Na[SbMe2]. Preparations for the other members of the series, o-C6H4(AsMe2)(SbMe2), o-C6H4(AsMe2)(NMe2), and o-C6H4(SbMe2)(NMe2), and for (o-methoxyphenyl)- and (o-methylthiophenyl)-dimethylphosphine o-C6H4(PMe2)Z (Z = OMe or SMe) are reported. The 1H and 31P n.m.r. and mass spectra of the ligands, intermediates, and quaternary derivatives are reported and discussed.

Complexes of bidentate group VB chelates : XIX. Mass spectral studies on some methyl-substituted bidentate group VB donor ligands☆

Abstract The fragmentation patterns of seven bidentate and two tridentate Group VB donor ligands are reported. For these methyl-substituted ligands the initial fragmentation is essentially loss of methyl radicals. Phenyl, but not methyl, migration occurs for the bis(phenylmethylarsino)alkanes, but methyl migration is evident in the all aliphatic bidentate chelates. The tridentate ligands PhE(CH2CH2CH2AsMe2)2 (E = P, As) show similar fragmentation routes, but are more complex. The long chain diarsine, Me2As(CH2)12AsMe2, exhibits a tendency to cyclise and lose C2H4 fragments progressively.

Mass spectra of disodium pamoate and an isomer by electron, chemical and fast atom bombardment ionisation

The El and Cl spectra of these two isomeric salts contained few high mass peaks. The positive and negative FAB spectra showed [M + H]+ and [M – H]– ions, respectively (where M is the disodium salt). Other strong peaks related to the structure were seen in the relative molecular mass region. The FAB spectra are useful for identifying these salts. For each ionisation technique there were differences between the spectra of the two isomers, but the major differences were observed in the El and Cl spectra. Either El or Cl spectra would be useful for differentiating these isomers.