Molecular species of sphingomyelin: determination by high-performance liquid chromatography/mass spectrometry with electrospray and high-performance liquid chromatography/tandem mass spectrometry with atmospheric pressure chemical ionization

1998 ◽  
Vol 33 (12) ◽  
pp. 1192-1198 ◽  
Author(s):  
Anders Å. Karlsson ◽  
Peter Michélsen ◽  
Göran Odham
2004 ◽  
Vol 22 (SI - Chem. Reactions in Foods V) ◽  
pp. S144-S146 ◽  
Author(s):  
S. Kemmo ◽  
V. Ollilainen ◽  
Lampi A-M ◽  
V. Piironen

A new specific method using high-performance liquid chromatography-mass spectrometry (HPLC-MS) for the detection of stigmasterol hydroperoxides was developed. Hydroperoxides of stigmasterol were obtained by photo-oxidation (90 min) in the presence of methylene blue as a sensitizer. The separation was performed using normal-phase chromatographic conditions. The MS detection was carried out with an ion-trap mass spectrometer using atmospheric pressure chemical ionization (APCI) and positive ion mode. Stigmasterol hydroperoxides were seen to produce no protonated molecular ions [M + H]<sup>+</sup> but instead fragments representing loss of one or two water molecules [M – H<sub>2</sub>O + H]<sup>+</sup>, [M – 2H<sub>2</sub>O + H]<sup>+</sup>, loss of hydrogen peroxide [M – H<sub>2</sub>O<sub>2</sub> + H]<sup>+</sup> or loss of hydrogen peroxide and water [M – H<sub>2</sub>O<sub>2</sub> – H<sub>2</sub>O + H]<sup>+</sup>. The results showed that positional isomers of hydroperoxides had different fragmentation patterns and relative ion abundances. On the other hand anomeric isomers had more similar fragmentation. As a conclusion the method developed showed to be a useful tool for investigation the oxidation mechanism of sterols.


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