MS2 spectra Precursor value in alignment result "Rep. vs. Ref" tab

August 11, 2023, 09:02:53 PM

Hi All,

One question about the MS2 spectra Precursor value in the alignment results "Rep. vs. Ref." tab, see the highlighted part with red rectangle in the picture. This value is not consistent with the measurement value (>0.1 Da difference). How is this MS2 spectra Precursor value obtained in MS Dial? I am manually curating this lipid, and I think for [M+H]+ the measurement doesn't match with the library since the measurement value 648.4619 is not consistent with library value 648.6289 due to >0.1 Da difference. But then I found this piece of info "MS2 spectra Precursor: 648.62781" on this tab. If the MS2 (DDA) is performed at this value, then the measurement value would match really good with library. I guess my question is how to make a right judgement based on these information.

Could anyone help? Thanks!

JL