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The utilized isotopic mass differences must be chosen from the list box of the
tool interface; the tolerances in ‘∆m/z’ and ‘∆ RT within scan [min]’ for this
check have to be specified in the two interface text boxes (Figure 25).
‘∆ RT within scan [min]’ should be set to a small value, since isotopologues
should elute with very similar RT.
Note: Since sorting along decreasing intensities, the routine assumes that nonmonoisotopic peaks (i.e. those with an isotopic mass difference relative to the
monoisotopic isotope composition) have a lower abundance (intensity) than
monoisotopic ones. While this is correct for most organic molecules,
discrepancies may arise for molecules having e.g. more than four Cl atoms. In
the latter case, isotopologue peaks would not be detected.
mass
Figure 25: Tool 12 for search of peaks within specific isotopic distances in
from potential monoisotopic peak masses.
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