Formation of Organometallic Species, [M – H]+ Ions and Radical Cations upon Mass Spectrometric Fragmentation of Mercury–Crown Ether Complexes

2009 ◽  
Vol 15 (4) ◽  
pp. 479-486 ◽  
Author(s):  
Rafał Frański ◽  
Błażej Gierczyk
Keyword(s):  
Mass Spectrometry ◽  
Crown Ether ◽  
Radical Cations ◽  
Mass Spectrometric ◽  
Tandem Mass ◽  
Fragmentation Pathways ◽  
Factors Influencing ◽  
Crown Ether Complexes ◽  
Mass Spectrometric Fragmentation ◽  
Ether Molecule

Mass spectrometric fragmentation pathways of [M + HgClO4]+ (M – crown ether molecule), determined by tandem mass spectrometry experiments, are discussed in detail. The decomposition of [M + HgClO4]+ proceeds along three fragmentation pathways: formation of [M – H]+ ions, formation of organometallic species, namely [M – H + Hg]+ ions, and formation of radical cations [M]+•. The factors influencing these processes, namely crown ether cavities and the presence of electron withdrawing/electron donor groups, have been discussed.

Gas-phase relative stabilities of Tl+-crown ether complexes and Rb+-crown ether complexes

2018 ◽  
Vol 24 (3) ◽  
pp. 279-288 ◽  
Author(s):  
Magdalena Frańska ◽  
Anna Michalak
Keyword(s):  
Mass Spectrometry ◽  
Crown Ether ◽  
Tandem Mass Spectrometry ◽  
Gas Phase ◽  
Collision Induced Dissociation ◽  
Tandem Mass ◽  
Ionic Radii ◽  
Relative Stabilities ◽  
Crown Ether Complexes ◽  
Cation Radius

The gas-phase stabilities of Tl+-crown ether complexes and Rb+-crown ether complexes were studied using the electrospray ionization-collision-induced dissociation-tandem mass spectrometry. Tl+ and Rb+ have identical ionic radii, thus a comparison of the properties of the crown ether complexes with these two cations seems to be justified. The selected crown ethers were 12C4 (it has a cavity smaller than the cation radius), 18C6 (it has a cavity of size similar to the cation radius), 24C8 (it has a cavity greater than the cation radius) and their conjugates. It has been found that the crown ether complexes of stoichiometry 1:1 with Tl+ are more or equally stable in the gas phase than the crown ether complexes with Rb+. However, 2:1 complexes with Tl+ are less stable than the complexes with Rb+.

Mass spectrometry of diamantane and some adamantane derivatives

1980 ◽  
Vol 58 (20) ◽  
pp. 2189-2195 ◽  
Author(s):  
Robert J. Waltman ◽  
A. Campbell Ling
Keyword(s):  
Mass Spectrometry ◽  
Hydrogen Atom ◽  
Mass Spectrometric ◽  
Adamantane Derivatives ◽  
Intensity Data ◽  
Metastable Peak ◽  
Fragmentation Pathways ◽  
Peak Intensity ◽  
Mass Spectrometric Fragmentation

The mass spectrometric fragmentation of adamantane, adamantane-d6, diamantane, 1- and 2-adamantanol, and 3,5,7-trimethyl-1-adamantanol has been re-examined, and new data for diamantane and 3,5,7-trimethyl-1-adamantanol are presented in more detail. Metastable peak data have been used to support potential fragmentation pathways. Simple statistical considerations applied to peak intensity data seem to indicate that ionization occurs at the primary bridgehead in both adamantane and diamantane, and that loss of a primary hydrogen is favored over loss of a secondary hydrogen atom.

Vitamin D analyses in veterinary feeds by gas chromatography-tandem mass spectrometry

2021 ◽  
pp. 146906672110002
Author(s):  
Andreas Lehner ◽  
Margaret Johnson ◽  
Alan Zimmerman ◽  
Justin Zyskowski ◽  
John Buchweitz
Keyword(s):  
Mass Spectrometry ◽  
Vitamin D ◽  
Gas Chromatography ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Vitamin D3 ◽  
Mass Spectrometric ◽  
Chromatographic Behavior ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry

This report examines the feasibility of determination of Vitamin D3, D2 and their 25-hydroxy metabolites utilizing Gas Chromatography Tandem Mass Spectrometry (GC/MS/MS) as a potential alternative to popular Liquid Chromatography Tandem Mass Spectrometric (LC/MS/MS) methodologies. The GC/MS/MS approach was found to operate reasonably well despite long-standing concerns that gas-liquid chromatography of vitamin D compounds invoke thermal rearrangements owing to the relatively high inlet and capillary column temperatures used. The workup procedure involved incubation of feed samples with concentrated potassium hydroxide for overnight fat saponification, extraction of D Vitamins in n-hexane and reaction with N,O-bis(trimethylsilyl)trifluoroacetamide at 70 °C for 30 mins. In addition to parent compounds, small amounts of pyro-, isopyro-, and iso-vitamin D and isotachysterol3 variants were obtained from each Vitamin D-related compound upon extraction and GC/MS/MS analysis. Mass spectral and chromatographic behavior of these compounds are herein described and interpreted. Multiple Reaction Monitoring settings on GC/MS/MS included m/z 456→351 for Vitamin D3 and m/z 486→363 for Vitamin D2. Trimethylsilylation enabled single predominant peaks for Vitamins D3 and D2, and sample workup in the presence of deuterated Vitamin D analogs enabled accurate and precise sensitivity to 1 ppb (ng/g) in feeds. The method could be extended with reasonable accuracy to 25-hydroxy (25OH) compounds, but accuracies would be significantly improved by inclusion of respective 25OH-specific deuterated internal standards. The method was applied to 27 submissions of suspect dog foods of which 22% were discovered elevated and 44% were discovered to contain toxic levels of Vitamin D3. The described method was thus discovered to provide a suitable mass spectrometric approach for Vitamin D, proving itself here specifically of value in detection of ergocalciferol and cholecalciferol in animal feeds. The specificity and sensitivity of the tandem quadrupole approach can enable suitable applicability to serum determination if desired.

scholarly journals Characterization and Study on Fragmentation Pathways of a Novel Nerve Agent, ‘Novichok (A234)’, in Aqueous Solution by Liquid Chromatography–Tandem Mass Spectrometry

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1059
Author(s):  
Jin Young Lee ◽  
Kyoung Chan Lim ◽  
Hyun Suk Kim
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Liquid Chromatography ◽  
Degradation Products ◽  
Aqueous Sample ◽  
Tandem Mass ◽  
Aqueous Samples ◽  
Fragmentation Pathways ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

As a first step toward studying the properties of Novichok (ethyl (1-(diethylamino)ethylidene)phosphoramidofluoridate (A234)), we investigated its degradation products and fragmentation pathways in aqueous solution at different pH levels by liquid chromatography–tandem mass spectrometry. A234 was synthesized in our laboratory and characterized by nuclear magnetic resonance spectroscopy. Three sets of aqueous samples were prepared at different pH levels. A stock solution of A234 was prepared in acetonitrile at a concentration of 1 mg/mL and stored at −20 °C until use. Aqueous samples (0.1 mg/mL) were prepared by diluting the stock solution with deionized water. The acidic aqueous sample (pH = 3.5) and basic aqueous sample (pH = 9.4) were prepared using 0.01 M acetic acid and 0.01 M potassium carbonate, respectively. The analysis of the fragmentation patterns and degradation pathways of A234 showed that the same degradation products were formed at all pH levels. However, the hydrolysis rate of A234 was fastest under acidic conditions. In all three conditions, the fragmentation pattern and the major degradation product of A234 were determined. This information will be applicable to studies regarding the decontamination of Novichok and the trace analysis of its degradation products in various environmental matrices.

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