Analyzing the Peak Purity
PPI and PPI Match Factor

In the chromatogram window of the PPA method, curves for the PPI (Peak Purity Index) and the Peak Purity Match Factor can be displayed:

• Double-click within the window and select the options Draw PPI and Draw Match from the Chromatogram Plot tab page.

The peak purity index is represented by a purple curve, and the match factor is indicated by a green curve. A distinctive rectangular shape is one criterion (of many) for peak purity. The exact match value at the current mouse pointer position is shown on the status bar. The ideal value is 1000 and requires approximately 80% of the available window height.

PPI, match value, and the corresponding standard deviation (RSD) can be included in a report. The report variables are available in the Peak Purity and Identification category.

The smaller the standard deviation, the more critical the quality of the rectangular curve should be judged; that is, the better the two spectra will match in various points of a peak.