Suppression of molecular ions in the secondary ion mass spectra of minerals

Liquid secondary ion mass spectrometry (LSIMS) and collision-induced dissociation (CID) were used for the characterization of sulfonamide derivatives of meso-tetraphenylporphyrin (TPP). The spectra obtained using LSIMS show abundant molecular ions and fragment ions from losses of the sulfonamide moieties. The main fragmentation observed in the LSI mass spectra and in the CID spectra of the protonated or cationized molecules involves the loss of one sulfonamide group. In addition, in the CID spectra of these compounds the fragment ions formed by the elimination of two, three and/or four sulfonamide groups are also observed. The CID spectra of the protonated or cationized molecules of these derivatives do not display the ions formed by the cleavage of the S - N bond which have been reported for other sulfonamide compounds. The LSI mass spectra and CID spectra of sulfonamide derivatives of meso-tetraphenylporphyrin provide an easy and reliable means of identification of the number and nature of sulfonamide groups in the porphyrinic ring.

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SUPPRESSION OF MOLECULAR IONS IN SECONDARY ION MASS SPECTRA

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1984232 ◽

1984 ◽

Vol 45 (C2) ◽

pp. C2-143-C2-146 ◽

Cited By ~ 1

Author(s):

N. S. McIntyre ◽

W. J. Chauvin ◽

J. B. Metson ◽

G. M. Bancroft

Keyword(s):

Mass Spectra ◽

Molecular Ions ◽

Secondary Ion

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Inductive effect in EI-mass spectra of some 5,6-dihalogenides and 5,6-halohydrins of 5α-cholestan-3β-ol and 3β-acetoxy-5α-cholestane

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19822946 ◽

1982 ◽

Vol 47 (11) ◽

pp. 2946-2960 ◽

Cited By ~ 1

Author(s):

Antonín Trka ◽

Alexander Kasal

Keyword(s):

Mass Spectra ◽

Inductive Effect ◽

Molecular Ions ◽

Hydroxyl Group ◽

Halogen Atoms ◽

Derivatives Of

Partial EI-mass spectra of 3β-hydroxy- and 3β-acetoxy-5α-cholestanes substituted in positions 5α-, 6β- or 5α,6β- with a hydroxyl group or halogen atoms (fluorine, chlorine, bromine) are presented. The molecular ions of 5α,6β-disubstituted derivatives of 3β-hydroxy-5α-cholestane (or of its 3-acetate) are considerably more stable than the corresponding monosubstituted derivatives if at least one of the pair of the vicinal substituents is chlorine or fluorine. This increase in stability, most striking in 5α- and 6β-fluoro compounds, is explained by the inductive effect.

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Mass spectra of 4,4-dimethyl-A-homo-4a,6-cholestadien-3-ols, 4,4-dimethyl-A-homo-5-cholestene-3,4a-diols and their derivatives

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19822768 ◽

1982 ◽

Vol 47 (10) ◽

pp. 2768-2778

Author(s):

Antonín Trka ◽

Helena Velgová

Keyword(s):

Carbon Atom ◽

Electron Impact ◽

Mass Spectra ◽

Molecular Ions

Partial electron impact induced mass spectra are given of 3α-hydroxy-, 3β-hydroxy-, 3β-methoxy-, 3α-acetoxy- and 3β-acetoxy-4,4-dimethyl-A-homo-4a,6-cholestadienes, 3α,5α-epoxy-4,4-dimethyl-A-homo-5-cholestane, isomeric 4,4-dimethyl-A-homo-5-cholestene-3α(β),4aα(β)-diols, their 3-acetoxy derivatives and 3-methyl ethers. The fragmentation of the molecular ions of these substances involves the usual elimination of substituents (in the form of H2O, CH3OH, CH3COOH, CH2CO), but the most abundant and characteristic ions are products of the contraction of ring A (to a six- or five-membered one), accompanied by expulsion of a fragment containing the carbon atom C(4) with both methyls.

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