Dear all,

Regarding the formation of adducts in LCMS, I would like to get ur valuable suggestion(s).
We are anlysing a compound having one acid group and sulphonic acid group,

I didn't observe any M+1 and M+18, but I got only M+36.

Is it possible for the formation of di adducts?
Is there any reference?
Advance thanks

Which solvent has you been used?
In that polarity has been analyzed?

It sounds like you are running in positive mode, since you are expecting M+1. With those functional groups, I suggest you try this compound in negative mode. Then you should see M-1, or if the molecule is large enough, maybe some (M-2)/2 in addition.

Dear MG,

Thanks for your suggestion.Yes I got M-1 peak.

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

1. I'm not sure I understand your question. The products will derive from whatever parent you have isolated. You can isolate whatever parent ion you want to: it can be a M+1 or M-1, a different adduct, or an up-front CID fragment. An adduct will sometimes fragment to yield M+1 or M-1 (I have seen it but have no explanation for it), but sometimes you will get other fragments.

2. I don't feel well qualified to answer this one, so take this with a grain of salt. It is my simple understanding that all daughters derive from the parent ion. In an ion trap, time spans are much longer, and this may not hold true.

3. Sorry, not at this time. There are quite a few of them, and you might have better luck searching for compound specific LC/MS/MS papers.

Dear MG,

Thanks for your suggestions.