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*   Using the Extracted Ion Chromatogram Features
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.
v
To display an XIC for a particular mass-to-charge ratio
1.
Click a spectral peak in the Scan pane.
–or–
Click the Data tab and double-click the m/z value in the mass-to-charge ratio table.
–or–
Click the Add/Edit Extracted Ion Chromatograms (XIC) button, .
The Extracted Ion Chromatograms dialog box opens.
2.
3.
Set a value of zero (the default value) to compare the XIC for m/z value with peaks using peak accuracy only.
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.
4.
5.
Click OK.
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.
Extracted ion chromatogram ion profiles


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Related Topics:
  Supported GC/MS and LC/MS Data File Formats
  Working in a Chromatogram Processor Window
  Using the Chromatogram Pane
  Averaging Scans
  Processing the Data
  Using Components Detection and Spectra Deconvolution
  Processing Extracted Spectra
  Working with Detected Components
  Processing MSn Data
  Exporting Scans, Components, and Reduced Chromatograms
  Annotating Chromatographic Peaks
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