Field desorption mass spectrometry of carboxylic acids: characteristic spectra and analysis of mixtures and impure samples

1978 ◽  
Vol 56 (10) ◽  
pp. 1372-1377 ◽  
Author(s):  
Gordon Walter Wooo ◽  
Emily Jane Oldenburg ◽  
Pui-Yan Lau ◽  
Donna Lee Wade
Keyword(s):  
Carboxylic Acids ◽  
Dicarboxylic Acids ◽  
Cross Product ◽  
Molecular Ions ◽  
Base Peak ◽  
Field Desorption ◽  
Technical Grade ◽  
Molecular Ion ◽  
Field Desorption Mass Spectrometry ◽  
Anode Temperature

Field desorption mass spectra were obtained for a variety of saturated and unsaturated carboxylic acids containing 12 or more carbons. At best anode temperature molecular ions were dominant and small peaks representing [M + 1]+, [2M + 1]+, [M − 17]+, and [Formula: see text] were present in several compounds. At higher temperatures several novel ions were found, including one corresponding to [2M + 1 – 18]+ which may represent anhydride formation. In a mixture of cis-5-eicosenoic and elaidic acids each molecular ion desorbed as expected but at higher temperatures the three possible anhydride ions appeared, with the cross product [M1 + M2 + 1 − H2O]+ as the base peak. Isomeric hydroxystearic acids (2-OH, 12-OH, 17-OH) gave predominantly ions in the molecular ion region with some differences in spectra which may relate to structure. Apparent polyester formation has been observed in 3-hydroxypropanoic acid where ions of the general formula [xM − (x − 1)H2O + H]+ with x = 2, 3, … 13 were found. Several other hydroxyacids show dimer formation and lactic acid has ions up to x = 5 in the above formula. Two of four technical grade dicarboxylic acids tested were seriously contaminated by sodium ions and gave useful spectra only after extraction by dibenzo-18-crown-6 ether. After this treatment both adipic and azelaic acid have [M + 1]+ as base peak, although adipic acid decarboxylates readily ([Formula: see text] = 74%) Other technical grade acids showed the presence of homologues and related structures as impurities.

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.

Polymerization in situ Accompanying Field Desorption Mass Spectrometry

1975 ◽  
Vol 53 (22) ◽  
pp. 3500-3502 ◽  
Author(s):  
Gordon Walter Wood ◽  
Donna Lee Wade
Keyword(s):  
Mass Spectrometry ◽  
Water Loss ◽  
Condensation Polymerization ◽  
Base Peak ◽  
Field Desorption ◽  
Desorption Mass Spectrometry ◽  
Hydroxycarboxylic Acids ◽  
Field Desorption Mass Spectrometry

Field desorption mass spectrometry of hydroxycarboxylic acids results in ions corresponding to condensation polymerization with water loss. The phenomenon is particularly marked with 3-hydroxypropanoic acid where at high anode temperatures the base peak corresponds to 6M – 5H2O and ions up to 13M – 12H2O are observed.

Field desorption mass spectrometry of carboxylate salts: characteristic spectra and effects of added complexing agents

1978 ◽  
Vol 56 (21) ◽  
pp. 2750-2754 ◽  
Author(s):  
Gordon Walter Wood ◽  
Emily Jane Oldenburg ◽  
Pui-Yan Lau
Keyword(s):  
Major Ions ◽  
Free Acid ◽  
Spectral Composition ◽  
Mass Range ◽  
Complexing Agents ◽  
Base Peak ◽  
Field Desorption ◽  
Polyhydroxy Compounds ◽  
Carboxylate Anions ◽  
Field Desorption Mass Spectrometry

Field desorption mass spectra are reported for a series of sodium carboxylates. Above 20 mA the major ions in the spectra belong to the series [xNa+ + (x − 1)RCOO−]+ with values of x normally extending throughout the measurable mass range. Desorption characteristics and spectral composition have been shown to be strongly modified by the addition of fructose and other polyhydroxy compounds. Thus, the sodium acetate spectrum is more intense and contains higher aggregates when 0.1–0.2 mol of fructose is added. With further additions the ionized free acid, AcOH+•, becomes the base peak in a low intensity spectrum recorded at 17–18 mA. The main ion from fructose is the sodium complex which does not exceed 20% of the base peak. Added fructose also has a beneficial effect on sodium 12-hydroxystearate but the improvement is less dramatic and there are some complications in the interpretation. A sample of technical lithium stearate contains the usual complexes up to [Li4(RCOO)3]+ and the presence of important amounts of palmitate gives rise to all possible combinations of the two carboxylate anions in these complexes. Smaller amounts of Li2Na, Li3Na, and Li3K complexed with the appropriate number of anions give evidence of alkali metal impurity.

Field Desorption Mass Spectra of Gastrine Peptides and Glutathione Derivatives

1979 ◽  
Vol 34 (5) ◽  
pp. 736-743 ◽  
Author(s):  
Michael Przybylski ◽  
Ingo Lüderwald ◽  
Ekkehard Kraas ◽  
Wolfgang Voelter ◽  
Sidney D. Nelson
Keyword(s):  
Mass Spectra ◽  
Peptide Bond ◽  
Molecular Ions ◽  
Sequence Information ◽  
Field Desorption ◽  
Field Desorption Mass Spectrometry ◽  
Fragmentation Reactions ◽  
Derivatives Of ◽  
Partial Sequence Information ◽  
Glutathione Derivatives

Oligopeptides comprising the sequence of the C-terminal tetrapeptide of gastrine, Trp-Met-Asp-Phe-NH2, and several derivatives of glutathione, γ-Glu-Cys(SR)-Gly, were characterized by field desorption mass spectrometry. The field desorption mass spectra obtained at various field ion emitter temperatures reveal abundant molecular ions and fragmentation reactions that yield partial sequence information. In the series of glutathione derivatives investigated, characteristic ions formed by cleavage of the γ-Glu-Cys peptide bond determine the substituent at the Cys residue and can therefore be used to identify corresponding conjugation products of drug metabolites with glutathione.

Field ionisation/field desorption mass spectrometry of polynuclear metal carbonyls

1980 ◽  
Vol 58 (8) ◽  
pp. 833-838 ◽  
Author(s):  
Dennis G. Tuck ◽  
Gordon W. Wood ◽  
Samuel Zhandhire
Keyword(s):  
Mass Spectrometry ◽  
Relative Abundance ◽  
Mass Spectra ◽  
Field Desorption ◽  
Metal Carbonyls ◽  
Desorption Mass Spectrometry ◽  
Molecular Ion ◽  
Field Desorption Mass Spectrometry

Field ionisation/field desorption mass spectra are reported for Mn2(CO)10, Cd[Co(CO)4]2 and some adducts, In[Co(CO)4]3, bipy•Zn[Co(CO)4]2, and bipy•M[Mn(CO)5]2 (M = Zn, Cd). The spectra are extremely simple, and the small number of easily identified species includes the molecular ion in some cases. The relative abundance of the fragments is discussed in terms of known stabilising factors in such compounds. No spectra could be obtained from Co2(CO)8 or Fe2(CO)9, which may be the result of their carbonyl-bridged structures.

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