Chromatography Forum

Hi !

I am doing forced degradation study on Waters UPLC. Is it true that in Empower software absorbance of peak of intrest shoud be less than 1.0 for peak purity? if yes, is there any link or article which stated same.

I do not think 1.0 au is a hard and fast rule, remember though that when the concentration of the analyte is high enough that detector linearity is exceeded at some wavelengths, the apex spectrum is different than others across the peak. This could result in spurious results.

I do not understand the statement:
absorbance of peak of intrest shoud be less than 1.0 for peak purity

why do we use absorbance of the peak as the parameter in force degradation study? I think resolution and peak purity based on the similarity of the spectra in certain positions of the peak are better to use.

If your peak gets a flat top, by saturating the detector, your peak purity isnt worth very much anymore.

The software takes the spectrum at the top of the peak and compare every other datapoint of the peak with this spectrum.
By saturating the detector, your reference spectrum isn't good anymore, and so is your peak purity.

On the other hand, if your absorbance is > 1, but your detector isn't saturated, then there is no problem at all

Ace