Chapter 5 Examining Spectrum Data

Manually calibrating a single spectrum

NOTE: Multi-point calibration yields higher mass accuracy than one-point calibration. Selecting calibrant peaks that bracket the mass of interest also yields higher mass accuracy.

To manually calibrate a single spectrum:

1.Click the Spectrum window to activate it, then select the spectrum trace of interest.

2.From the Peaks menu, select Peak Label, set the Mass Label Type to Centroid, then click OK.

NOTE: For spectra containing broad peaks that have unresolved adducts or impurities such as proteins, you may obtain better results if you use apex instead of centroid settings.

3.From the Process menu, select Mass Calibration, then select Manual Calibration.

The Manual Mass Calibration dialog box is displayed (Figure 5-2).

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