Studies in Mass Spectrometry. VII. Triterpenoids: Ifflaionic Acid

1963 ◽  
Vol 16 (4) ◽  
pp. 683 ◽  
Author(s):  
JS Shannon
Keyword(s):  
Mass Spectrometry ◽  
Methyl Ester ◽  
Functional Groups ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Keto Group ◽  
Chemical Derivatives ◽  
Pentacyclic Triterpenoid

The mass spectra of the methyl ester of the new unsaturated pentacyclic triterpenoid ifflaionic acid (urs-12-en-3-on-30-oic acid) and some of its chemical derivatives are presented. These may be used to assign position C-20 to the carbomethoxy and C-3 or C-7 to the keto group. Mechanistic proposals for, and the effect of functional groups on, the main fragmentation of the molecular ions (cleavage through ring C) are discussed.

scholarly journals Confirmation of Indandione Rodenticide Toxicoses by Mass Spectrometry/Mass Spectrometry

1992 ◽  
Vol 4 (4) ◽  
pp. 441-446 ◽  
Author(s):  
W. Emmett Braselton ◽  
Regg D. Neiger ◽  
Robert H. Poppenga
Keyword(s):  
Mass Spectrometry ◽  
High Performance ◽  
Mass Spectra ◽  
Similar Case ◽  
Molecular Ions ◽  
Sample Introduction ◽  
Physical Evidence ◽  
Direct Exposure ◽  
Mass Spectrometry Mass Spectrometry ◽  
Isotope Cluster

Mass spectrometry/mass spectrometry (MS/MS) with collision-activated dissociation (CAD) was utilized to unequivocally distinguish 1,3-indandione rodenticides in 2 cases of anticoagulant toxicosis. Anecdotal evidence provided by the veterinarian in a case involving feedlot cows and physical evidence at the site of occurrence in a similar case involving lambs strongly implicated diphenadione (diphacinone; DP) in both instances. However, high performance liquid chromatography indicated chlorophacinone (CP), not DP, was present in the blood samples obtained from both cows and lambs. Intact 1,3-indandiones exhibit poor gas chromatographic properties, so procedures were developed for analysis by MS/MS using a direct exposure probe for sample introduction. The EI mass spectra of DP and CP contained a base peak at m/z 173, with molecular ions (M+) at m/z 340 and m/z 374 (Cl isotope cluster), respectively. Corresponding MS/MS CAD parent ion spectra of m/z 173 showed an ion of m/z 340 for DP and 374 (Cl cluster) for CP. CAD analysis of the blood extracts showed a parent ion scan of m/z 173 identical to that of CP, with the m/z 374 (Cl cluster). (Additional evidence was obtained by MS/MS examination of the CAD daughter ion spectrum of m/z 374.) Blood extracts from the affected animals revealed CAD daughter ion spectra for m/z 374 identical to that of reference CP. Positive confirmation of CP in both cases led to identification of the source of the toxicant and prevention of further animal exposures.

Fast Atom Bombardment Mass Spectra of Some N-α-(t-Butoxycarbonyl)-O-(diorganylphosphono)-L-serines and O-(Diorganylphosphono)seryl-Containing Dipeptides and Tripeptides

1994 ◽  
Vol 47 (2) ◽  
pp. 229 ◽  
Author(s):  
JW Perich ◽  
I Liepa ◽  
AL Chaffee ◽  
RB Johns
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
High Intensity ◽  
Mass Spectra ◽  
Fast Atom Bombardment ◽  
Molecular Ions ◽  
Operating Conditions ◽  
Negative Ion ◽  
The Matrix ◽  
Positive Ion

Positive and negative ion fast atom bombardment ( f.a.b .) mass spectrometry were found to be useful methods for the analysis and structural characterization of five Nα-(t- butoxycarbonyl )-O-( diorganylphosphono )-L- serines ( organyl = Ph, Et, Me, Bzl , But), especially in the case of the sensitive benzyl and t-butyl phosphono derivatives. Under positive ion operating conditions, high intensity pseudo-molecular ions were obtained in the f.a.b . mass spectra, and the fragmentation pathway of the phenyl, ethyl and methyl derivatives was established by parent/daughter linked scanning studies to involve (a) the two-step loss of the t- butoxycarbonyl group, (b) loss of the amino acid as the neutral fragment from the [MH]+, [MH-56]+, [MH-100]+ and [MH-146]+ ions by a four- centred β-elimination rearrangement, and (c) cleavage of the phosphono phenyl and ethyl groups from only the [(RO)2P(OH)2]+ and [NH=CHCH2PO3R2+H]+ fragments. Parent/daughter linked scanning studies of the benzyl derivative showed that the prominent fragmentation involved loss of the benzyl group as the tropylium ion and that the 'apparent' [MH-90]+ peak observed in its f.a.b. mass spectrum resulted from cleavage of the phosphono benzyl group in the matrix during the bombardment process. In the case of the t-butyl derivative, parent/daughter linked scanning studies showed that the prominent fragmentation involved successive 'in-flight' loss of the phosphono t-butyl groups as isobutene. Negative ion f.a.b. mass spectrometry of the five derivatives gave f.a.b. mass spectra which displayed distinct [M-H]- anions along with high intensity [M-H-R]- and [(RO)2PO2]- fragment anions, the f.a.b . mass spectrum of the t-butyl derivative containing an additional [M-H-But-But]- fragment anion. Parent/daughter linked scanning studies established that the majority of the observed fragment anions resulted from extensive fragmentation of the Boc -Ser(PO3R2)-OH derivatives in the matrix phase followed by sputtering of the resultant fragments into the gas phase. In addition, positive ion f.a.b . mass spectrometry was found to be useful for the analysis of a series of protected O-( diorganylphosphono ) seryl-containing dipeptides and tripeptides ( organyl = Ph, Et, Me, Bzl ). The obtained spectra showed that β-elimination fragmentation of the Ser(PO3R2) residue was more pronounced with the tripeptide series and indicated that there was increased sensitivity of the O-( diorganylphosphono ) seryl residue with replacement of the Boc group by an amino acyl residue at its N-terminus.

Field Desorption Mass Spectrometry of Mycotoxins and Mycotoxin Mixtures, and Its Application as a Screening Technique for Foodstuffs

1977 ◽  
Vol 60 (1) ◽  
pp. 73-82 ◽  
Author(s):  
James A Sphon ◽  
Peter A Dreifuss ◽  
Hans-Rolf Schulten
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Field Desorption ◽  
Desorption Mass Spectrometry ◽  
Screening Technique ◽  
Field Desorption Mass Spectrometry

Abstract The field desorption mass spectra of a variety of mycotoxins have been studied. These include the 4 aflatoxins B1, B2, G1; and G2, rubratoxin B, T-2 toxin, and zearalenone, as well as mixtures of these mycotoxins. The spectra of all of the mycotoxins exhibited molecular ions [M]+. Under the conditions employed, only rubratoxin B exhibited major fragmentation. The field desorption technique has been applied to the analysis of both spiked and naturally contaminated extracts of foodstuffs. The potential of the method as an analytical screening technique for the presence of mycotoxins has been evaluated.

Liquid Secondary Ion Mass Spectrometry and Collision-induced Dissociation Mass Spectrometry of Sulfonamide Derivatives of meso-Tetraphenylporphyrin

1999 ◽  
Vol 03 (03) ◽  
pp. 172-179 ◽  
Author(s):  
M. ROSÁRIO M. DOMINGUES ◽  
M. GRAÇA SANTANA-MARQUES ◽  
A. J. FERRRER-CORREIA ◽  
AUGUSTO C. TOMÉ ◽  
MARIA G. P. M. S. NEVES ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Secondary Ion Mass Spectrometry ◽  
Molecular Ions ◽  
Collision Induced Dissociation ◽  
Fragment Ions ◽  
Ion Mass Spectrometry ◽  
Derivatives Of ◽  
Secondary Ion

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.

Mass Spectrometry: The Elimination of CO from Substituted Nitro Naphthalenes

1966 ◽  
Vol 21 (3) ◽  
pp. 210-213 ◽  
Author(s):  
J. H. Beynon ◽  
B. E. Job ◽  
A. E. Williams
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Electron Density ◽  
Mass Spectra ◽  
Molecular Ions

The mass spectra of 1-nitronaphthalene, 2-nitronaphthalene and eight substituted nitro naphthalenes have been studied. The loss of neutral CO from the molecular ions of these compounds has been established by high resolution techniques and study of “meta stable” peaks. The probability of elimination has been related to the electron density at the 8-position.

Ligand Exchange in FAB Mass Spectrometry of Monomerie and Dimeric Corrinoids

1984 ◽  
Vol 39 (11) ◽  
pp. 1548-1552 ◽  
Author(s):  
Lutz Grotjahn ◽  
Ludger Ernst
Keyword(s):  
Mass Spectrometry ◽  
Ligand Exchange ◽  
Mass Spectra ◽  
Fast Atom Bombardment ◽  
Molecular Ions ◽  
Negative Ion ◽  
Fab Mass Spectrometry ◽  
Fab Mass Spectra

Abstract In the Fast Atom Bombardment (FAB) mass spectra of monomeric and dimeric corrinoids, exchange of metal-bound ligands against matrix particles is observed which leads to pseudo molecular ions. Negative ion FAB mass spectra in particular, give distinct information on the intact molecular units.

Electron ionization mass spectrometry of cobalt(III) β-diketonates and monothio-β-diketonates possessing aryl and fluorinated alkyl substituents

1992 ◽  
Vol 70 (3) ◽  
pp. 952-963 ◽  
Author(s):  
Mark L. J. Reimer ◽  
John B. Westmore ◽  
Manoranjan Das
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Fluorine Content ◽  
Molecular Ions ◽  
Electron Ionization ◽  
Ionization Mass ◽  
Chelate Complexes ◽  
Neutral Species ◽  
Positive Ion ◽  
Marked Dependence

Electron ionization positive ion mass spectra of 15 substituted cobalt(III) β-diketonates and monothio-β-diketonates, CoIIIL3, where L = RCXCHCOR′, R = phenyl, 2-thienyl, or 2-naphthyl; X = O or S; and R′ = CHF2, CF3, C2F5, or n-C3F7, show a marked dependence on the ligand. Molecular ions, [CoIIIL3]+•, are observed only for some of the more highly fluorinated complexes (R′ = C2F5 or n-C3F7). The [CoIIIL2]+• ion, possibly generated by ionization of CoIIL2 formed by thermal degradation, or by electron ionization of CoIIIL3, typically decomposes by elimination of a radical, i.e., L• or R′•, to yield ions containing Co(II); subsequent decompositions proceed preferentially by loss of even-electron neutral species, also to yield ions containing Co(II). Cobalt-containing ions in which fluorine has rearranged to the metal decrease in variety and abundance for the ligands with higher fluorine content. When metal-bonded oxygen is replaced by sulfur, fluorine migration to Co(III), rather than to Co(II), is preferred. These trends are consistent with a combination of several different concepts including the ability of the metal to undergo valency change, the principle of Hard and Soft Acids and Bases, and the inductive capabilities of the ligand donor atoms and of the R and R′ groups. Ion decomposition pathways are proposed. Keywords: mass spectrometry, cobalt complexes, β-diketonates, fluorinated chelate complexes.

Studies on the mass spectrometry of some acyclic nuclear substituted styryl ketoximes and ketones with special reference to the ortho effect

1979 ◽  
Vol 57 (22) ◽  
pp. 2908-2915 ◽  
Author(s):  
C. B. Nyathi ◽  
J. R. Dimmock ◽  
L. M. Smith
Keyword(s):  
Mass Spectrometry ◽  
Special Reference ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Fragmentation Pathways ◽  
Total Absence ◽  
Cyclization Process ◽  
Steric Factors ◽  
Acyclic Ketones ◽  
Ortho Substituent

The mass spectra of several ring substituted acyclic styryl ketoximes and analogous ketones have been determined at 70 eV and also at low ionization voltages. The major fragmentation pathways for the oximes are loss of the ortho substituent from the parent ion as well as loss of the hydroxyl and hydroxylamine radicals. Other fragmentation pathways include γ- and δ-cleavages as well as the McLafferty rearrangement. While there was a total absence of α-cleavage from the parent ions, the facility of loss of the ortho substituents from the oxime molecular ions was compared with the same process occurring in the corresponding acyclic ketones, as well as the related cyclic derivatives, namely the substituted 2-benzylidinecyclohexanones and oximes. Stabilization of the resultant cyclized ion as well as steric factors are considered as factors favouring the cyclization process.

Studies in Mass Spectrometry. I. Structures and Reactions of Ions from Benzyl Alcohol, ortho-, meta-, and para-Hydroxybenzyl Alcohols, and their 0-Deuterated Derivatives

1962 ◽  
Vol 15 (2) ◽  
pp. 265 ◽  
Author(s):  
JS Shannon
Keyword(s):  
Mass Spectrometry ◽  
Benzyl Alcohol ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Complex Structures ◽  
Π Complex ◽  
Rearrangement Reactions ◽  
Hydroxybenzyl Alcohol

The work described in the present paper, which was undertaken in the course of investigations into the mass spectra of coal and coal fractions, led the author to propose mechanisms of dissociation and rearrangement reactions of ions derived from benzyl alcohol and from o-, m-, and p-hydroxybenzyl alcohol on the basis of a study of; (i) the mass spectra of these latter compounds, including comparable features in the mass spectra of 1,4-cyclohexadiene and O-deuterated o- and p-cresols; (ii) the mass spectra of the corresponding 0-deuterated benzyl and hydroxybenzyl alcohols; (iii) meta-stable transitions. π-Complex structures may play an important role in the dissociation of some of the ions-for example, in the loss of D2O from molecular ions of m- and p-hydroxybenzyl alcohols.

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