Some Aspects of the Mass Spectra of.N-Nitrosamines

The mass spectra of seven cyclic N-nitrosamines were examined for characteristic fragmentation patterns. Accurate mass measurements on three of the compounds indicated that the M-17 and M-30 peaks resulted from molecular ion losses of •OH and •NO respectively. The loss of • OH was rationalized in terms of a McLafferty-type rearrangement.

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Electron ionization mass spectra of bis-1,2,4-oxadiazoles: tandem mass spectrometry and accurate mass measurements

Rapid Communications in Mass Spectrometry ◽

10.1002/rcm.305 ◽

2001 ◽

Vol 15 (11) ◽

pp. 884-888 ◽

Cited By ~ 3

Author(s):

Rajendra M. Srivastava ◽

L. A. B. Moraes ◽

M. N. Eberlin

Keyword(s):

Mass Spectrometry ◽

Tandem Mass Spectrometry ◽

Mass Spectra ◽

Electron Ionization ◽

Accurate Mass ◽

Ionization Mass ◽

Tandem Mass ◽

Mass Measurements ◽

Accurate Mass Measurements ◽

Electron Ionization Mass Spectra

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Electron impact studies. XII. Mass spectra of substituted imidazoles

Australian Journal of Chemistry ◽

10.1071/ch9671613 ◽

1967 ◽

Vol 20 (8) ◽

pp. 1613 ◽

Cited By ~ 70

Author(s):

JH Bowie ◽

RG Cooks ◽

S Lawesson ◽

G Schroll

Keyword(s):

Mass Spectrometry ◽

Structure Elucidation ◽

Mass Spectra ◽

Molecular Ions ◽

Skeletal Rearrangement ◽

Mass Measurements ◽

Exact Mass ◽

Metastable Ions ◽

Characteristic Fragmentation ◽

Fragmentation Patterns

The mass spectra of 37 imidazoles are reported and discussed. The spectra exhibit pronounced molecular ions and characteristic fragmentation patterns. The fragmentation modes have been substantiated by deuterium labelling, exact mass measurements, and appropriate metastable ions. Skeletal rearrangement fragments are rare in these spectra; consequently mass spectrometry is useful for structure elucidation of imidazoles.

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Contributions to the Interpretation of Mass Spectra of the TEOS Methoxy-Transesters. Linked Scans, Accurate Mass Measurements and M+1, M+2 Isotopic Effects

Revista de Chimie ◽

10.37358/rc.20.8.8277 ◽

2020 ◽

Vol 71 (8) ◽

pp. 39-54

Author(s):

Virgil Badescu

Keyword(s):

Mass Spectra ◽

Structural Formula ◽

Molecular Ions ◽

Accurate Mass ◽

Mass Measurements ◽

Electronic Impact ◽

Accurate Mass Measurements ◽

Fragmentation Reactions ◽

Double Focusing ◽

Isotopic Effects

The aim of this article is the study of the fragmentation reactions of the methoxy-transesters of tetraethoxysilane (TEOS), with structural formula (CH3O)x(C2H5O)ySi, initiated by electronic impact in the ionization chamber of a double focusing mass spectrometer. The initiation centers of fragmentation reactions for the neutral and ionized TEOS methoxy-transesters were established by quantum calculations of net atomic charges. The ions of the mass spectra of the TEOS methoxy-transesters were obtained experimentally by the B/E and B/E(1-E)1/2 linked scans. Thus, there can be written the fragmentation pathways for the primary events by B/E linked scan (cleavage of methoxy and ethoxy groups) and eliminations of neutral molecules (acetaldehyde, ethylene, formaldehyde, molecular hydrogen) by B/E(1-E)1/2 linked scan. Accurate mass measurements at high resolution (5000), double bond equivalent (DBE) for the molecular ions and fragmentation ions of the TEOS methoxy-transesters and M+1, M+2 isotopic effects were used to confirm their identification. The reaction pathways and accurate mass in mass spectrum of dimethoxydiethoxysilane (TR2M) are detailed.

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Differentiation of the Isomeric o-(m- and p-) Nitro-(Chloro- and Bromo-)Benzyl-2,4-(and 2,1-) Disubstituted 2-Thiocytosinium Halides by Electron Impact Ionisation and Fast Atom Bombardment Mass Spectrometry

European Journal of Mass Spectrometry ◽

10.1255/ejms.996 ◽

2009 ◽

Vol 15 (4) ◽

pp. 497-506 ◽

Cited By ~ 2

Author(s):

Tomasz Pospieszny ◽

Elżbieta Wyrzykiewicz

Keyword(s):

Mass Spectrometry ◽

Mass Spectra ◽

Fast Atom Bombardment ◽

Collision Induced Dissociation ◽

Mass Measurements ◽

Fragmentation Pathways ◽

Mass Spectral ◽

Fragment Ions ◽

Accurate Mass Measurements ◽

Impact Ionisation

Electron ionisation (EI) and fast atom bombardment (FAB) mass spectral fragmentations of nine 2,4-(and 2,1-) disubstituted o-( m- and p-)nitro-(chloro- and bromo-)-2-thiocytosinium halides are investigated. Fragmentation pathways, whose elucidation is assisted by accurate mass measurements and metastable transitions [EI-mass spectrometry (MS)], as well as FAB/collision-induced dissociation (CID) mass spectra measurements are discussed. The correlations between the abundances of the (C11H10N4SO2)+1–3; (C11H10N3SCl)+4–6 and (C11H10N3SBr)+7–9 ions and the selected fragment ions (EI-MS), as well as (C18H16N5SO4)+1–3; (C18H16N3SCl2)+4–6 and (C18H16N3SBr2) + 7–9 ions and the selected ions (C7H6NO2)+1–3; (C7H6Cl)+ 4–6; (C7H6Br)+ 7–9 (FAB-MS) are discussed. The data obtained can be used for distinguishing isomers.

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Electron Impact Ionization Mass Spectra of 3-Amino 6-Chloro2-methyl Quinazolin-4-(3H)-one Derivative

10.47363/jmsmr/2021(2)114 ◽

2021 ◽

pp. 1-5

Author(s):

Osarumwense Peter Osarodion ◽

◽

Omotade Treasure Ejodamen ◽

Keyword(s):

Electron Impact ◽

Mass Spectra ◽

Impact Ionization ◽

Cyclic Compound ◽

Electron Impact Ionization ◽

Ionization Mass ◽

Fragmentation Pattern ◽

Molecular Ion ◽

Mass Spectral ◽

Characteristic Fragmentation

Looking at the previous studies on quinazolinones derivatives, only limited information’s are available on their mass spectral along with the preparation of novel quinazolin-4-(3H)-one derivatives The condensation of Methyl-2-amino-4-Chlorobenzoate with acetic anhydride yielded the cyclic compound 2-methyl 7-Chloro-1, 3-benzo-oxazine-4-one (1) which further produce 3-Amino-2-Methyl 7-Chloro quinazolin-4(3H)-ones (2) via the reaction with hydrazine hydrate. The compounds synthesized were unequivocally confirmed by means of Infrared, Nuclear Magnetic Resonance (1H and 13C), Gas Chromatography-Mass spectrophotometry and Elemental analysis. Discussion: The molecular ion of m/z 235 fragments to give m/z 220 by loss of –NH group. The ion of m/z 220 was broken to give m/z 206 by losing CH2 group and fragment to m/z 177 by loss of HCO. This fragmented to m/z 162 by loss of –CH3 group and then m/z 136 by loss of CN group. The loss of O gave m/z 120 which fragment to give m/z 93 by loss of –HCN and finally gave m/z 65 by loss of CO group. Conclusion: The electron impact ionization mass spectra of compound 2show a weak molecular ion peak and a base peak of m/z 235resulting from a cleavage fragmentation. Compound 2 give a characteristic fragmentation pattern. From the study of the mass spectra of compound 2, it was found that the molecular ion had fragmented to the m/z 220. The final fragmentation led to ion of m/z 93 and ion of mass m/z 65, respectively

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Characterization and identification of flavonoids from Bambusa chungii leaves extract by UPLC-ESI-Q-TOF-MS/MS

Acta Chromatographica ◽

10.1556/1326.2020.00777 ◽

2020 ◽

Author(s):

Ting Yuan ◽

Xue-Feng Guo ◽

Si-Yue Shao ◽

Rong-Miao An ◽

Jin Wang ◽

...

Keyword(s):

High Performance ◽

Gradient Elution ◽

High Definition ◽

Bamboo Leaves ◽

Fat Reduction ◽

Accurate Mass Measurements ◽

Acid Aqueous Solution ◽

Characteristic Fragmentation ◽

Fragmentation Patterns ◽

Tof Ms

AbstractBamboo leaves extract (BLE) has a variety of physiological functions such as antitumour, anti-inflammatory, antioxidant and blood fat reduction activities and the flavonoids of bamboo leaves are the major active constituents. To profile the flavonoids in the complex BLE, a rapid and sensitive analytical method based on ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) was developed for the structural identification of the flavonoids in Bambusa chungii leaves extract using accurate mass measurements and characteristic fragmentation patterns. After separation on an Agilent SB-C18 Rapid Resolution High Definition (RRHD) column (2.1 mm × 150 mm, 1.8 μm) by gradient elution with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase, the sample was analysed by ESI-QTOF-MS/MS in the negative mode. A total of 22 flavonoids were detected, and eight of these were identified by comparison with reference standards, while the other fourteen were tentatively identified according to their MS/MS data. The main fragmentation pathways of flavonoid C-glycosides (compounds 1, 5 and 10), flavonoid di-C,O-glycosides (compound 4), flavonoid di-C-glycosides (compound 7) and flavonoid C,O-di-glycosides (compounds 2 and 14) are shown in this article. This is the first report on the analysis of the flavonoids in the extract of B. chungii leaves. The present work demonstrates that UPLC-ESI-Q-TOF-MS/MS is an efficient technique for identifying multiple flavonoids of BLE.

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