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Peak List
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Software User’s Guide 3-43
3
2. Select Enable Peak List Filter, then select:
Filter Type Description
Monoisotopic Labels the peak of the lowest detected mass in an isotope
envelope. Before applying filtering, set the values in Peak
Processing detection parameters to accurately detect and label all
peaks in the isotope envelope with the correct charge state. If the
parameters are not correctly set to yield correct charge states for
all peaks, the monoisotopic peak may not be correctly labeled.
See Section 3.2.5, Charge State Determination and Examples, for
more information on setting parameters.
Monoisotopic filtering is useful on isotope clusters where the
approximate elemental composition and isotopic ratios are not
known, for example, in PSD analysis (where the precursor ion
filtering enhances the precursor ion isotope intensity relative to the
rest of the cluster), or in a spectrum that contains molecules with
very different elemental compositions.
For most applications, especially peptide analysis, the deisotoping
function yields more accurate results than monoisotopic peak
filtering. See Section 3.4, Deisotoping a Spectrum.
Charge State Labels the peaks with the selected charge state (z). If you select a
charge state of 0, the software displays mass labels only on peaks
for which the software could not determine a charge state.
CAUTION: A zero value in the Spec Peak list does not indicate a
charge state of zero. It indicates that the software could not
determine the charge state.