Chapter 4 Examining Chromatogram Data

Labeling spectrum peaks with mass difference (optional)

Procedure

4

You can label spectrum peaks with mass differences to assist you in determining the mass differences to specify in the CNL extracted chromatogram.

To label spectrum peaks with mass differences:

1.Display a spectrum of interest from the data file for which you are creating the CNL extracted chromatogram.

2.Click the Spectrum window to activate it, then select Peak Label from the Peaks menu.

3.In the Peak Mass Label Type, select Mass difference from the selected peak.

4.In the Spectrum window, right-click-drag across the peak from which you are measuring the difference. This enters a negative value that corresponds to the reference peak in the text box.

5.Click OK. The reference peak is labeled with zero, and all the other peak labels are plus or minus their mass difference from the reference peak.

For more information on peak labels, see Section 3.5, Peak Labeling.

To create a CNL extracted chromatogram:

1.Click the Chromatogram window to activate it.

2.Select Duplicate Active Trace from the Display menu to keep the original data displayed after processing.

3.From the Process menu, select Extracted Ion or click

in the toolbar.

The Extracted Ion Chromatogram dialog box appears (Figure 4-3).

4.In the Mass Range/Difference Type field select Neutral Loss.

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