scholarly journals Mass-spectrometric study of the azopigments obtained from bile pigments with diazotized ethyl anthranilate

1970 ◽  
Vol 120 (4) ◽  
pp. 891-894 ◽  
Author(s):  
F. Compernolle ◽  
F. H. Jansen ◽  
K. P. M. Heirwegh
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
Mass Spectra ◽  
Mass Spectrometric Study ◽  
Side Chain ◽  
Bile Pigments ◽  
Trimethylsilyl Derivative ◽  
Spectrometric Study ◽  
Human Bile ◽  
Rat Bile

The structures of some azopigments obtained by diazotization of conjugated and unconjugated bile pigments with diazotized ethyl anthranilate were studied by mass spectrometry. The α0-azopigments derived from rat bile and human bile were shown to be identical (t.l.c. and mass spectra) with azobilirubin derived from unconjugated bilirubin. The presence of two methyl vinyl isomers (Ia) and (Ib) in equal amounts was shown by t.l.c. and mass spectrometry. The structure of the δ-azopigment derived from rat bile was studied by two methods: (a) ammonolysis gave rise to an amide having a CH2·CH2·CO·NH2 side chain as shown by its mass spectrum; (b) the mass spectrum of a trimethylsilyl derivative of the δ-azopigment methyl ester confirmed the ester to be a β-d-monoglucuronide ester of azobilirubin I.

scholarly journals Spectrometric Study of the Nitrile-Ketenimine Tautomerism

2009 ◽  
Vol 2009 ◽  
pp. 1-18 ◽  
Author(s):  
Hebe Saraví Cisneros ◽  
Sergio Laurella ◽  
Danila L. Ruiz ◽  
Agustín Ponzinibbio ◽  
Patricia E. Allegretti ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Mass Spectrum ◽  
Magnetic Resonance ◽  
Mass Spectra ◽  
Spectrometric Study ◽  
Mass Spectral ◽  
Ion Fragmentation ◽  
Nuclear Magnetic Resonance Spectra ◽  
Amination Product

Mass spectrometry is used to evaluate the occurrence of the nitrile-ketenimine tautomerism. Mass spectra of two differently substituted nitriles, ethyl-4,4-dicyano-3-methyl-3-butenoate and diethyl-2-cyano-3-methyl-2-pentenodiate are examined looking for common mass spectral behaviors. Ion fragmentation assignments for specific tautomers allow to predict the presence of the corresponding structures. Additionally, the mass spectrum and nuclear magnetic resonance spectra of ethyl-4,4-dicyano-2,2-diethyl-3-methyl-3-butenoate and that of the corresponding amination product support the occurrence of the ketenimine tautomer in the equilibrium.

Mass spectrometry of the vapours over PbBr2+MBr mixtures (M = Na, K, Rb, Cs)

1971 ◽  
Vol 24 (10) ◽  
pp. 2001 ◽  
Author(s):  
H Bloom ◽  
RG Anthony
Keyword(s):  
Mass Spectrometry ◽  
General Formula ◽  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Enthalpies Of Formation ◽  
Second Law ◽  
Spectrometric Study ◽  
Complex Molecules ◽  
Bipyramidal Structure

A mass spectrometric study of vapours above molten PbBr2+MBr mixtures has revealed the existence of vapour species of general formula MPbBr3 (M = Na, K, Rb, Cs). Second-law enthalpies of formation of these complexes were found to be in the range -39 to -44 kcal/mol; entropies of formation are estimated between -20 to -21 e.u. It is believed that these complex molecules have a bipyramidal structure.

scholarly journals Gas chromatographic-mass spectrometric study of metabolites of C21 and C19 steroids in neonatal porcine testicular microsomes

1985 ◽  
Vol 227 (3) ◽  
pp. 909-916 ◽  
Author(s):  
T K Kwan ◽  
N F Taylor ◽  
D Watson ◽  
D B Gower
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Spectrometric Study ◽  
Selected Ion Monitoring ◽  
17 Hydroxyprogesterone ◽  
Porcine Testis ◽  
Steroid Pathway ◽  
Chromatographic Mass

Microsomal fractions obtained from testes of 3-week-old piglets have been incubated, separately, with progesterone, 17-hydroxyprogesterone, 5-pregnene-3 beta,20 beta-diol, 16 alpha-hydroxypregnenolone, 5-androstene-3 beta,17 alpha-diol and dehydro-epiandrosterone. The metabolites, after derivatization, have been separated by capillary gas chromatography and identified by mass spectrometry. Quantification was by selected ion monitoring. Progesterone was shown to be 17-hydroxylated and also converted into 4,16-androstadien-3-one (androstadienone). The major metabolite of 17-hydroxyprogesterone was 4-androstene-3,17-dione (4-androstenedione), but little, if any, androstadienone was formed, indicating that this particular biosynthesis did not require 17-hydroxylation. The metabolites of 5-pregnene-3 beta, 20 beta-diol were found to be 17-hydroxypregnenolone, 3 beta-hydroxy-5,16-pregnadien-20-one (16-dehydropregnenolone) and 5,16-androstadien-3 beta-ol. Dehydroepiandrosterone and 5-androstene-3 beta,17 alpha-diol were interconvertible but neither steroid acted as a substrate for 16-androstene formation. However, dehydroepiandrosterone was metabolized to a small quantity of 4-androstenedione. Under the conditions used, no metabolites of 16 alpha-hydroxypregnenolone could be detected. The present results, together with those obtained earlier, indicate that the neonatal porcine testis has the capacity to synthesize weak androgens, mainly by the 4-en-3-oxo steroid pathway. Although 16-androstenes cannot be formed from C19 steroids, progesterone served as a substrate and may be converted directly to androstadienone, without being 17-hydroxylated first. The pathway to 5,16-androstadien-3 beta-ol, however, involves 17-hydroxypregnenolone and 16-dehydropregnenolone as intermediates.

Fast Atom Bombardment Mass Spectrometry of the Vitamin B12 Analogues Hydrogenobalamin and Cupribalamin

1984 ◽  
Vol 39 (2) ◽  
pp. 248-251 ◽  
Author(s):  
Lutz Grotjahn ◽  
Volker B. Koppenhagen ◽  
Ludger Ernst
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrum ◽  
Mass Spectra ◽  
Fast Atom Bombardment ◽  
Metal Clusters ◽  
Cobalt Atom ◽  
Vitamin B ◽  
Metal Free ◽  
Characteristic Fragment ◽  
Fab Mass Spectra

Hydrogenobalam in (metal-free vitamin B12) and cupribalamin are characterized by their fast atom bombardment (FAB) mass spectra which show molecular ion and characteristic fragment ion peaks. These spectra and the high-resolution FAB mass spectrum of cobalamin (vitamin B12) show that the (M+H)+-CN-59 peak for the latter is due to loss of acetamide and not of the central cobalt atom. In the FAB mass spectrum of cupribalamin metal clusters are observed

The isolation of 11-oxotetrahydrorhombifoline from Ormosia coutinhoi and a study of its mass spectrum

1967 ◽  
Vol 45 (7) ◽  
pp. 751-757 ◽  
Author(s):  
Stewart McLean ◽  
A. G. Harrison ◽  
D. G. Murray
Keyword(s):  
Mass Spectrum ◽  
Electron Impact ◽  
Mass Spectra ◽  
Equilibrium Theory ◽  
Side Chain ◽  
Fragmentation Reaction ◽  
Quasi Equilibrium ◽  
Molecular Ion ◽  
Dihydro Derivative ◽  
A Minor

11-Oxotetrahydrorhombifoline (I) has been isolated from the alkaloidal extract of the bark of Ormosia coutinhoi, and its dihydro derivative II has been prepared. An examination of the mass spectra of these compounds and of their 3,3-d2 derivatives has led to the elucidation of the course of the major electron impact induced fragmentations undergone by the molecules. The main fragmentation of I leads to loss of C3H5 from the side chain to form an ion of m/e 221, with a minor path involving a central fission of the molecular ion to form an ion of m/e 150. The mass spectrum of II shows that the loss of C3H7 to form the ion of m/e 221 is a minor process, the main fragmentation reaction involving a central fission to form an ion of m/e 152 analogous to the ion of m/e 150 from I. This change in the spectrum is shown to be consistent with predictions based on the quasi-equilibrium theory of mass spectra.

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.

Compounds of aziadamantane type: Mass spectrometric study

1989 ◽  
Vol 54 (3) ◽  
pp. 691-698 ◽  
Author(s):  
Sergei D. Isaev ◽  
Nataliya F. Karpenko ◽  
Aleksandr G. Yurchenko ◽  
Luděk Vodička ◽  
Valentin I. Kadentsev ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrometric Study ◽  
Nitrogen Molecule ◽  
Molecular Ions ◽  
Mass Spectrometric ◽  
Spectrometric Study ◽  
Molecular Ion ◽  
Mechanism Of Decomposition ◽  
Derivatives Of ◽  
Type Mass

Azi and hydrazi derivatives of adamantane,adamantanone and diamantane were studied by mass spectrometry. The EI spectra of azi derivatives lack completely molecular ions; the presence of abundant dehydroadamantane or dehydrodiamantane ions corresponds to elimination of nitrogen molecule from the molecular ion. Comparison of the EI ionization with photolysis or pyrolysis allowed to deduce some analogies and to suggest the mechanism of decomposition of the molecular ion.

Synthesis and NMR and mass spectrometric study of ammonioacetohydrazones of formylphenylboronic acids as novel ionic prospective sugar receptors

2015 ◽  
Vol 39 (6) ◽  
pp. 4695-4707 ◽  
Author(s):  
Grażyna Bartkowiak ◽  
Łukasz Popenda ◽  
Stefan Jurga ◽  
Grzegorz Schroeder
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrometric Study ◽  
Maldi Mass Spectrometry ◽  
Mass Spectrometric ◽  
Spectrometric Study ◽  
Receptor Molecule ◽  
Ionic Group ◽  
Sugar Receptors

We report sugar receptors in which the sensitivity of detection through MALDI mass spectrometry is enhanced due to the introduction of an ionic group to the receptor molecule.

Sign in / Sign up

Export Citation Format

Share Document