L. Nizigiyimana et al., COMPARISON OF LOW-ENERGY AND HIGH-ENERGY COLLISION-INDUCED DISSOCIATION TANDEM MASS-SPECTROMETRY IN THE ANALYSIS OF RICINOLEIC AND RICINELAIDIC ACID, Journal of mass spectrometry., 32(3), 1997, pp. 277-286
Ricinoleic acid and its trans isomer ricinelaidic acid, and their meth
yl esters, were analyzed by low- and high-energy collision-induced dis
sociation (CID) tandem mass spectrometry. It is shown that a stable ch
arge centre is required to observe the rearrangement, which occurs in
the beta-hydroxyalkene part and results in the loss of heptaldehyde, a
nd that this rearrangement corresponds to a low-energy CID reaction. D
ifferences between the CID behaviour of ricinoleic acid and that of it
s trans isomer are related to the loss of water, which can also be reg
arded as a low-energy rearrangement reaction. Comparison of low- and h
igh-energy CID spectra further revealed that high-energy CID gives ris
e to loss of a H-. radical and H-2 together with low-energy fragmentat
ion. Examination of different molecule ions, including [M - H](-), [M
+ Li](+) and [M - H + 2Li](+) ions of free fatty acids and [M + Li] ions of the methyl esters shows that charge-remote homolytic fragmenta
tion is most pronounced for the [M + Li](+) ions of the methyl esters.
(C) 1997 by John Whey & Sons, Ltd.