Studies in chemical ionization mass spectrometry 10—CI(CH₃NH₂) spectra of olefins

Gas chromatography–vacuum ultraviolet spectroscopy for analysis of fatty acid methyl esters

“…Studies also show that electron impact ionization tends to cause http://dx.doi.org/10.1016/j.foodchem.2015.08.004 0308-8146/Ó 2015 Elsevier Ltd. All rights reserved. double bond migration (Budzikiewicz & Busker, 1980), which leads to ambiguous results regarding the structure of the FAs.…”

Acetonitrile Chemical Ionization Tandem Mass Spectrometry To Locate Double Bonds in Polyunsaturated Fatty Acid Methyl Esters

“…CI single-stage MS methods have employed a variety of reagent gases including vinylamine, , vinyl methyl ether either alone or as a mixture with N 2 , N 2 and CS 2 , or CO 2 , , methylamine, isobutane, , OH - produced by EI in a 10:90 ratio of N 2 O to CH 4 , and NO. − Budzikiewicz et al report that the double bonds in methylene-interrupted triene and tetraene systems can be located by two radical-ion fragments using NO as the reagent gas . In general, the disadvantage to CI-based methods reported to date is that they are limited to special cases and have only been evaluated for localization of a maximum of four double bonds.…”

Chemical ionization mass spectrometry with amines as reactant gases. II—amine chemical ionization mass spectrometry of diene valepotriates

“…The specific elimination of the three acyloxy substituents at C(1), C(7) and C ( 11) in the different reactant gases allows the determination of their exact location. Thus, the type of acyloxy substituent at C(7) can be determined from ion u7[M + R3NH -R3N -R7COOH]+ in the ammonia CI spectra.…”

“…Thus, the type of acyloxy substituent at C(7) can be determined from ion u7[M + R3NH -R3N -R7COOH]+ in the ammonia CI spectra. The substituent at C (11) can be established from either ion b'[M + R3NH -R3N -R'COOH -R7COOH]+, using Et3N or NH3, or ion d[M + MeNH, -R'COOH -R+7COOH]+, using MeNH,. Therefore, the use of different amines as reactant gases can be considered as complementary methods.…”