By Anonymous on Wednesday, March 10, 2004 - 12:45 am:
As I am new to LC/MS/MS, The fragmentation pattern and adduct formation is confusing (earlier I worked in GCMS, where the fragmentation is different) Expecting your valuable suggestions about the following queries,
1. Suppose I am getting my mass as M+18 or M+1 what about the MS/MS fragments mass? Is it M+18 or M+1 or M+? similarly in negative mode.
2. The product ions in the lower mass are fragmenting from parent ion or from one of the daughter ion?
3. Can you give us some references for the MS/MS fragmentation in LC/MS/MS.
Advance thanks
By Anonymous on Wednesday, March 10, 2004 - 03:05 am:
It will be confusing while using different terms, usually parent ion and product ion will be good terms to understand the fragmentation pattern. In LC/MS/MS, being analysing through selective reaction monitoring, we have to think for the parent ion and respective product ion. The parent ion may be M+1 or M+23 (or others, by adduct formation). Mostly protonated parent ion (M+1) is used, but some time adduct formation with sodium or ammonium can also be used. One thing keep in mind....the product ion must be from the parent ion. You can get breakdown curve of your parent ion directly from your instrument(by tuning the instrument with the compound). The SRM mode, which is the highest sensetivity among different parent>product ions, is used for analysis.
I hope it will be helpful for you.
By Anonymous on Thursday, March 11, 2004 - 06:50 pm:
Thanks for your suggestion.
Is the product ion (frgamentation from parent ion) is M+1 or M or M+2?, Is it depends on the chemistry? or something else.
Thanks
By Anonymous on Friday, March 12, 2004 - 04:30 am:
Parent ion is M+1 or M+Na, product ion is any of the stable breakdown products because of the collision induced degradation. Product ion formation depends on the molecular structure of the compund. Usally week bonds (or any functional group) may break to result product ion. The product ion always less than the M (or M+1, or M+Na). Na is sodium. The basic principle of LC-MS/MS is monitoring parent ion (M+1, or M+Na) following breakdown product through collision induced by colliding gas. I hope it will make you more clear about the parent and product ion.