Peak Purity Match Factor

The Match Factor expresses the similarity of two curves. A peak purity match factor can be expressed for both UV spectra and mass spectra.

The match factor for UV spectra (= UV match factor) refers to the correlation between the spectrum in the peak maximum and the spectra on the leading and trailing edges. Ideally, none of the spectra between peak start and peak end deviates from the spectrum in the peak maximum. They correspond to 100%; that is, the match value is 1000. For Mass Spectra, the distance between the single masses and the relative height of the different mass peaks is taken into account. As with UV spectra, a match factor of 1000 indicates a perfect match. However, the MS match factor is far more selective than the UV match factor.

 Tip:

The calculation of the match factor becomes more inaccurate on the peak margins. This is due to the poorer Signal-to-Noise Ratio. Select the Peak Purity Threshold detection parameter to limit the selection of the UV and mass spectra in the QNT Editor (see Data Representation and Reprocessing  The QNT Editor) to a sensible peak height.

If the match factor of a peak is included in a report column, the value will be averaged from all match values of the peak that have been determined so far. The UV match factor is always baseline-corrected (see Baseline Correction of Spectra), as this portion usually cannot be neglected; it would falsify the result.

With mass spectra, define in the QNT Editor whether background mass spectra shall be subtracted. If you enable background subtraction, define which spectra shall be subtracted. This also defines whether the match factor shall be output baseline-corrected. For more information, refer to  Subtracting MS Background Spectra.

In addition, you can include the deviation of the averaged single match values in the PPA Report as the Peak Purity: Relative Standard Deviation of the Match Factor (RSD Match).