Use the Mass Frontier application to display a chromatogram for an extracted ion in a
different color. The extracted ion chromatogram (XIC) is sometimes called an individual, or single ion chromatogram, ion profile. The program can display up to 16 extracted ion chromatograms per window.
You can use background subtraction in conjunction with the Extracted Ion Chromatogram
feature. In this case, the XIC profiles are extracted from background-subtracted scans.
Click the Data
tab and double-click the m/z
value in the mass-to-charge ratio table.
Set a non-zero value of tolerance (± m/z
value) to compare the peak m/z
value/accuracy with “XIC for m/z”
± its tolerance.
The application extracts the XIC from the original file, a process that can be
time-consuming for chromatograms with a large number of scans. However, because the application is multi-threading, you can still use other windows during the XIC extraction.
An extracted ion chromatogram is useful for verifying automated component detection and
spectra deconvolution results. An XIC helps you to recognize mixture components in a peak region. Examine an XIC of model peaks for any component you might want to use in further analysis. Some structural (alkanes) or optical isomers produce almost identical mass spectra, and even if you can clearly see two or more maxima in a peak region, an XIC might not reveal a multi-component profile.
An XIC can help you determine whether the composition of the background changes over the
course of a run. To view the background profile, extract the XIC of a base peak or a prominent peak from a scan that is clearly in a non-peak region. If the XIC of a background peak has a variable profile around the peak you are focusing on, choose two scans with different XIC profiles for background subtraction.