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Topic: Why Matches from Post identification do not show a respective MS2 match? (Read 2689 times) previous topic - next topic

Why Matches from Post identification do not show a respective MS2 match?

Dear all,

for identification purpose I used post identification (txt file) as well as MS2 spectra annotation using the open-source msp-file from the website.
If I had a closer look into the data, I recognized that in any case when I got a match by post identification there was no respective MS2 match, although most of these features had a good MS2 spectrum. Therefore, and because I know that some of these analytes are present in the spectral library, I expected an MS2 match, too. But only the post identification result is reported in the annotation table and the feature list, respectively.

Can I find the result from MS2 matching of the "postident matching features" somewhere else?
If not, what is happening with features that are matched by post identification? ArenĀ“t they considered for subsequent MS2 annotation?

Thanks in advance.

Best regards,
FalcoB

Re: Why Matches from Post identification do not show a respective MS2 match?

Reply #1
I am having the same issue. If I include a post-identification text library, is it possible to get RT, m/z and MS2 matches factored into the total score?

I am using MONAs LCMS spectral library (msp) which does contain MS2 for the entries in my text library. I have included the text library because of the RT info which I would like to leverage for identifications.

@Hiroshi Tsugawa can you help?