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

✍ Scribed by Karlsson, Anders Å.; Michélsen, Peter; Odham, Göran

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 144 KB
• Volume: 33
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199812)33:12<1192::aid-jms735>3.0.co;2-j

✦ Synopsis

In a sphingomyelin-enriched sample of polar lipids from bovine milk, molecular species of intact sphingomyelin were separated by normal-phase high-performance liquid chromatography and detected by mass spectrometry (MS) for structural information. First, by using electrospray with positive ionization (ESI), protonated molecules ( [ M + H ] ') were detected. Second, in atmospheric pressure chemical ionisation (APCI+ ), in-source fragmentation of sphingomyelin ions led to the formation of ceramide ions. With the ceramide ions as precursors, ions representative of both the long-chain base (LCB) parts and the fatty acid (FA) parts were detected in APCI-MS/MS via collision-induced decomposition (CID). Using this procedure, it was possible to determine the sphingomyelin molecular masses using ESI+ and then their respective LCB-FA combinations(s) using APCI+ -MS/MS. At least 36 protonated molecules of intact sphingomyelin were detected in the bovine milk sample. The combinations found covered a range of molecular masses from 673 to 815 Da. The 12 most common protonated molecules (constituting ¿90% of the total ion current in ESI) were composed of at least 25 di †erent LCB-FA combinations. Saturated and unsaturated LCBs and FAs were detected in addition to hydroxy fatty acids. The most common LCBs were 16 : 1, 17 : 1, 18 : 1 and 19 : 1, whereas the most common FAs were 16 : 0, 22 : 0, 23 : 0 and 24 : 0. LCB-FA combinations of sphingomyelin from bovine brian, bovine erythrocytes and chicken egg yolk are also presented.