Fronting

[DR]

Make sure that the wavelength changes are not going to add undue variability (instrument to instrument).

If you can't separate PVP from your peak, could you prepare your standards in PVP? At least you should be able to integrate consistently.

Does the partition coefficient for PVP change with temperature? Maybe a refrigerated centrifuge could help.

[syx]

Thank you, DR.
The validation is in progress to see it can be used or not.
PVP is not too 'dangerous' in the condition.

We do not try the temperature effect to PVP, unless our latest method is not valid. But, we are worried that the refrigerate will reduce the solubility of substance 2.