Hi, Sangita -

Can you clarify your question a bit?  The first part suggests that you got good information about sphingomyelin fragmentation from several articles; the second part seems to be asking for the same information.

With respect to the ion at m/z 184.4, that's an ion that should be present in most, if not all, of that class of compounds (http://www.sfrbm.org/pdf/LC-MS_oxidized-phospholipids_Pitt_FRBM2011.pdf) .  So, if you have a complex mixture, and are interested only in members of the class, you could do precursor-ion scans (http://medical-dictionary.thefreedictionary.com/precursor+ion+scan) on that m/z and get  chromatograms with the molecular ions ([M+H]+) for each of them.  Then - depending on your instruments - you could either set up automatic product-ion scans (http://medical-dictionary.thefreedictionary.com/product+ion+scan) on those ions during the same run or re-analyze the sample in product-ion mode on the highlighted m/zs to help identify the individual compounds.

Dear Wishnok,

Thank you for your response. I have attached the data file in inbox to elaborate my questions. The above response is helpful too.

Sangita

Hey Sangita,

It has been a long time since you made this question but the same question just occured to me. I haven't been able to find the other [M+H]+ fragments of sphingomyelins in positive mode ESI MS in the articles that I read, and wanted to ask if finally you were able to answer this question back then.

Of course if somebody else has an answer he is more than wellcome to help.

Thank you