You can calculate purity values to check for contaminations, for example, from coeluted peaks. The purity values are calculated by comparing all spectra recorded for a specific peak with the spectrum at the peak apex.
Prerequisites
To be able to carry out the procedure as described, you need the privilege Processing Method > Edit spectra parameters. Privileges are configured in the Control Panel.
If the project enforces method approval, the method status must be Generic. For details, see Method approval.
In the Processing Method window, select the Compounds > Spectra node.
In the UV Impurity Check tab, enter the following parameters:
Calculate UV Purity
Select to calculate values for all integrated peaks or for identified peaks only. Select None if you do not want to calculate values for any peaks.
Lower wavelength [nm], Upper wavelength [nm]
Wavelength range to use for the impurity check. By default, the whole range is used.
Sensitivity unidentified peak [%]
By changing the sensitivity value(default: 50 %), you influence the Threshold calculation and thus the criteria for a green or red coloring of the UV Purity value in the injection results.
Threshold exceptions
Number of data points in a row that are allowed below the threshold line. See Adapt the threshold exceptions.
In the Compound Table tab, adjust the sensitivity for identified compounds in the Impurity sensitivity [%] column.
Click Reprocess All.
UV purity results for the selected peak are shown in the following windows:
In the Injection Results window
In the Chromatogramswindow
In the Peak Detailswindow