Donor-atom effects in the mass spectra of complexes of dipivaloylmethane and its monothio and dithio analogues

1976 ◽  
Vol 29 (2) ◽  
pp. 257 ◽  
Author(s):  
CG Macdonald ◽  
RL Martin ◽  
AF Masters
Keyword(s):  
Mass Spectra ◽  
Mixed Ligand ◽  
Donor Atom ◽  
Mass Spectral ◽  
Fragment Ions ◽  
Nickel Compounds ◽  
Spectral Peaks ◽  
Electron Impact Mass ◽  
Ligand Species ◽  
Impact Mass

The progressive replacement by sulphur in the isostructural planar nickel compounds bis(2,2,6,6- tetramethylheptane-3,5-dionato)nickel(11) (1), bis(2,2,6,6-tetramethyl-5-thioxoheptan-3-onato)nickel(11) (2) and bis(2,2,6,6-tetramethylheptane-3,5-dithionato)nickel(11) (3) causes a change in their positive electron impact mass spectra from one dominated by metal-containing fragment ions (1) to one But 1 dominated by oxidized ligands (3). Comparisons are also made with the spectra of tris(monothio-dipivaloylmethanato)cobalt(111) and bis(1,l,1-trifluoro-4-thioxopentan-2-onato)nickel (11). Mass spectral peaks corresponding to mixed ligand species were observed when mixtures of (1) and (2) were vaporized in the mass spectrometer.

scholarly journals Combination of LC-MS2 and GC-MS as a Tool to Differentiate Oxidative Metabolites of Zearalenone with Different Chemical Structures

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Andreas A. Hildebrand ◽  
Erika Pfeiffer ◽  
Georg Damm ◽  
Manfred Metzler
Keyword(s):  
Mass Spectra ◽  
Ion Trap ◽  
Hydrolysis Product ◽  
Chemical Structures ◽  
Ion Trap Mass Spectrometer ◽  
Fragment Ions ◽  
Oxidative Metabolites ◽  
Electron Impact Mass ◽  
Negative Electrospray Ionization ◽  
Impact Mass

Recent studies on the mammalian and fungal metabolism of the mycotoxin zearalenone (ZEN) have disclosed the formation of six regioisomers of monohydroxy-ZEN and its reductive metabolite zearalenol (ZEL). Hydroxylation occurs at the aromatic ring or at one of four positions of the aliphatic macrocycle. In addition, an aliphatic ZEN epoxide, its hydrolysis product, and other products were identified in fungal cultures. In this paper, we report the product ion spectra of the [M-H]− ions of 22 oxidative metabolites of ZEN and ZEL, obtained by LC-MS2 analysis using a linear ion trap mass spectrometer with negative electrospray ionization. The MS2 spectra exhibit qualitative and quantitative differences which allow a clear distinction of most metabolites. Moreover, GC-MS analysis of the trimethylsilylated metabolites yields electron impact mass spectra with numerous fragment ions which can be used as fingerprint to confirm the chemical structure derived by LC-MS2 analysis.

Survey of Computer Aided Methods for Mass Spectral Interpretation

1981 ◽  
Vol 35 (3) ◽  
pp. 255-266 ◽  
Author(s):  
David P. Martinsen
Keyword(s):  
Mass Spectra ◽  
Search Pattern ◽  
Comprehensive Treatment ◽  
Mass Spectral ◽  
Spectral Interpretation ◽  
Interpretive Methods ◽  
The Status ◽  
Electron Impact Mass ◽  
Impact Mass

Recent studies in the application of computerized techniques to mass spectral interpretation have been reviewed. The techniques have been divided into library search, pattern recognition, and interpretive methods. The more common methods in use in each category, as well as the more recent methods, are discussed. Earlier review articles are referenced for a more comprehensive treatment of earlier methods. The status of the large libraries of electron impact mass spectra is discussed and a number of attempts at improving the quality of those libraries are detailed.

Spectres de masse d'hydrazino-2 benzo- et naphtothiazoles et d'hydrazones des méthyl-3 benzo- et naphtothiazolinones-2

1975 ◽  
Vol 53 (23) ◽  
pp. 3677-3680 ◽  
Author(s):  
Jean-Claude Richer ◽  
Philippe Lapointe ◽  
Martine Beljean ◽  
Michel Pays
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
Base Peak ◽  
Molecular Ion ◽  
Ion Fragmentation ◽  
Fragment Ions ◽  
Sampling Probe ◽  
Electron Impact Mass ◽  
Impact Mass ◽  
Hydrazone Form

Electron impact mass spectra are reported for the hydrazones of 3-methyl-2-benzothiazolinone (1), of 4-, 5-, 6-, and 7-chloro-3-methylbenzo-2-thiazolinones (2, 3, 4, and 5) and of 3-methyl-naphtho[2,1-d]-2-thiazolinone (6), as well as for 2-hydrazinobenzothiazole (7), for 4-, 5-, 6-, and 7-chloro-2-hydrazinobenzothiazoles (8, 9, 10, and 11) and for 2-hydrazinonaphtho[2,1-d]thiazole (12). The results obtained in the two series are compared. The 2-hydrazone and 3-methyl-benzo-2-thiazolinone and its derivatives all form a base peak corresponding to the molecular ion; fragmentation proceeds mainly by successive losses of·NH2, HCN, HCN, and then CS. Initial losses of N2H2, NH·, and NH3 are minor fragmentation routes.In the case of 2-hydrazinobenzothiazole and its derivatives, the base peak is still that of the molecular ion; however, the relative proportions of the various fragment ions vary with the position of sampling probe inside the apparatus. Thus it is concluded that the observed mass spectrum is that of a mixture of the possible hydrazone-hydrazine tautomers. The principal fragmentations involve the initial loss of NH3 (leading to a stabilized ion), of NH2· (probably from the hydrazone form), and of N2H2.(Journal Translation)

Gas Chromatographic and Mass Spectrometric Determination of Ametryn and Its N-Dealkylated Products

1984 ◽  
Vol 67 (5) ◽  
pp. 904-909
Author(s):  
Promode C Bardalaye ◽  
Willis B Wheeler ◽  
James L Templeton
Keyword(s):  
Gas Chromatography ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
Gas Chromatography Mass Spectrometry ◽  
Ionization Mass ◽  
Mass Spectral ◽  
Methane Chemical Ionization ◽  
Electron Impact Mass ◽  
Impact Mass

Abstract Gas chromatographic and mass spectrometric properties of ametryn and its N-dealkylated products were studied to establish the potential use in a recently reported method describing the residue analyses of these compounds by gas chromatography with N-P detection. Electron impact mass spectra show base peaks at the molecular ion (M+), and methane chemical ionization mass spectra give base peaks at (M + 1) ion for all the compounds studied. Characteristic mass spectral fragmentations of ametryn, GS-11354, GS-11355, and GS-26831 are presented. Combined gas chromatography-mass spectrometry rather than gas chromatography alone provides unambiguous residue characterization. The technique also allows quantitation of ametryn and its N-dealkylated products that cochromatograph with interfering materials present in a complex substrate.

Notizen: Fast Pulsed Laser Induced Electron Generation for Electron Impact Mass Spectrometry

1988 ◽  
Vol 43 (12) ◽  
pp. 1151-1153 ◽  
Author(s):  
E. R. Rohwer ◽  
R.C. Beavis ◽  
C. Köster ◽  
J. Lindner ◽  
J. Grotemeyer ◽  
...  
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Ion Source ◽  
Electron Impact Mass Spectrometry ◽  
Uv Laser ◽  
Electron Generation ◽  
Medium Resolution ◽  
Electron Impact Mass ◽  
Impact Mass ◽  
Tof Ms

A new ultra fast electron impact (El) ion source is pre­sented that produces a very short, high intensity electron beam, allowing medium resolution mass spectra to be re­corded without pulsing the ion accelerating voltages in a time-of-flight mass spectrometer (TOF-MS). The ion source requires minimum modification of any TOF-MS equipped with an electrostatic ion reflector and UV-laser. El-spectra are presented for comparison with literature spectra.

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

2009 ◽  
Vol 15 (4) ◽  
pp. 497-506 ◽  
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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