Chromatography Forum

Hi,

I am currently developing a SEC method for the determination of Polyvinyl alcohol (PVA) for a certain finished product. My problem is that the product matrix contains another Polymer called Hydroxyethyl cellulose which comes almost at the same retention time as PVA (circa 10 minutes). My question therefore would be if anyone knows what changes I could perform to separate these peaks via mobile phase, temperature, pH etc or sample preparation. The problem is that both polymers are water soluble otherwise I could play with the organic composition of the mobile phase.

Currently, I am dissolving the PVA standard in water and the product sample as well.

The mobile phase is water.
Column: Shodex806 300 x 7.5
The column temperature 30°C
Detection mode: RI
Flow rate: 1 ml/min

Many thanks in advance!

MP

What about using UV detection? Run UV spectra of both and see if there's a wavelength where you can selectively detect the PVA.

What about using UV detection? Run UV spectra of both and see if there's a wavelength where you can selectively detect the PVA.

Both Polymers have no chromophore, that's why I have to go for an RI or ELSD-Detector. So far we have used an old UV/Vis-method which works via a boric acid - iodine complex but its not meeting the ICH validation criteria.

Both Polymers have no chromophore,

Duh!! I should have known that.

So, on to "plan C". The catch is that with SEC there is little you can do via the mobile phase to affect selectivity short of changing the conformation of one of the molecules (and I know next to nothing about polymer chemistry, so I can't even guess as to how that might be accomplished).

Enzymatic hydrolysis as part of sample prep maybe???

Both Polymers have no chromophore,

Duh!! I should have known that.

So, on to "plan C". The catch is that with SEC there is little you can do via the mobile phase to affect selectivity short of changing the conformation of one of the molecules (and I know next to nothing about polymer chemistry, so I can't even guess as to how that might be accomplished).

Enzymatic hydrolysis as part of sample prep maybe???

Thanks for the tip with the enzymatic hydrolysis! I know there are some cellulases out there that might be useful. Otherwise I was thinking about freeze drying.