Integration
The Mass Spectra Plot

General

The Mass Spectra Plot enables the display of Mass Spectra. The prerequisite for opening the mass spectra plot is that the corresponding raw data recorded by a Mass Spectrometer are available. Open the mass spectra from the Integration method.

• To open the spectra plot, select Show Mass Spectra on the View menu or click the following icon: .

The representation of a mass spectrum is height normalized: The height of the spectrum is represented in percent and thus independent of the concentration (also, refer to Normalization). As a default, this normalization is by the Base Peak of the spectrum.

Normalization allows you to objectively compare two spectra of different concentrations. If mass spectra of the same peak, but from different peak heights are overlaid, these will generally coincide despite the differences in concentration. Due to their higher information density, mass spectra are displayed in Chromeleon below each other, which is contrary to the display of UV spectra that are overlaid.

Displaying Mass Spectra of one Peak

• In the chromatogram plot, select the peak for which to display the mass spectrum (= spectrum in the peak maximum).

• If several peak heights were enabled on the Peak Spectra tab page in the Decoration dialog box of the mass spectra plot, the mass spectra from different peak heights are displayed simultaneously when you click a peak.

Displaying Mass Spectra of Different Samples

To compare mass spectra of different samples objectively:

• Select Decoration on the context menu of the spectrum to open the Decoration dialog box and select the Peak Spectra tab page.

• Select the Retention time spectrum of fixed sample option and click Browse to navigate to the sample of interest.

• Alternatively, you may also use the retention time spectrum of the last standard (= Retention time spectrum of recent standard), the reference spectrum of the peak table (= Reference spectrum in corresponding peak table), or any spectra that was found during library screening (Spectra library screening result).