MS2 Spectra containing fragment mass same as precursor ion
Posted: Sun Sep 08, 2019 9:11 pm
Hi All,
I've some MSMS data (MGF files) for which I've found that there is a fragment mass almost equal to the mass of the precursor ion with highest abundance among the msms peaks, and some masses greater than the precursor. Is this something uncommon suggesting that the precursor is not adequately fragmented and formed adduct masses larger than the precursor?
Secondly, for the mass 457.5577859, can it result due to a loss of water molecule?
I'm enclosing part of the ms2 spectra with fragments sorted by their abundances. The third colums shows the relative abundance compared to the most abundant ms2 peak.
I've some MSMS data (MGF files) for which I've found that there is a fragment mass almost equal to the mass of the precursor ion with highest abundance among the msms peaks, and some masses greater than the precursor. Is this something uncommon suggesting that the precursor is not adequately fragmented and formed adduct masses larger than the precursor?
Secondly, for the mass 457.5577859, can it result due to a loss of water molecule?
I'm enclosing part of the ms2 spectra with fragments sorted by their abundances. The third colums shows the relative abundance compared to the most abundant ms2 peak.
Code: Select all
BEGIN IONS
TITLE=C31 "controllerType=0 controllerNumber=1 scan=81"
RTINSECONDS=81.0765
PEPMASS=463.220001220703 2351077.0
CHARGE=3+
463.8945914 750950.5 100
457.5577859 266115.2813 35.43712685
360.6910986 194093.5781 25.84638776
457.2216554 173094.5625 23.05006289
646.3289232 146484.1875 19.50650376
668.2983467 109999.5469 14.6480423
439.5647401 107747.8906 14.34820146
577.7872263 98013.15625 13.05187975
577.2840984 95289.23438 12.68914987
645.8266372 92351 12.29788115
361.1934364 87724.55469 11.68180255
439.2308563 62405.16797 8.310157323
463.5589927 60907.16406 8.110676278
464.2267778 54563.89453 7.265977522
451.8826723 47210.08203 6.286710247
451.556398 45388.90234 6.044193638
669.2975931 41486.14063 5.524484054
646.8317955 39324.73828 5.236661841
425.219467 37794.64063 5.032907046