Inject 2 M urea on a Dionex HPAEC-PAD system ?

[goran123]

Hi,

Someone told me recently that it is OK to inject 2 M urea (after PNGase F treatment, to cleav off N-linked glycans from glycoproteins) on a Dionex ICS 3000 HPAEC-PAD system, with a PA 100 column.

Does the Dionex system really tolerate 2 M urea injections?
Have someone tested?

Urea is partly converted to ammonium cyanate, which is accelerating at increased temperature (I incubate with PNGase F overnight at 37 C) and at elevated pH (pH is about 13 in the Dionex eluents).

If I dare to test it, I will deprotonize the sample by SPE RPC, or something similar, before injecting on the Dionex system.

I have just started to use the Dionex system and I am very grateful for advice.

Best regards,

Goran Karlsson
Octapharma
Stockholm

[Chris Pohl]

goran123,

Since urea is nonionic there is no problem with injecting it into an anion exchange column such as a CarboPac PA 100. It should elute cleanly in the void. The only thing you have to worry about is the viscosity of the sample. If the viscosity is too high, repeated injections can cause column damage. In the case of 2M urea the sample viscosity is reasonable so this shouldn't be a concern. I'm certain that others have analyzed samples containing 2M urea without issue so I wouldn't worry about it.

Chris

[Mark Tracy]

I talked to a glyco-chemist, and she has used graphitic carbon cartridges to remove urea. Look at www.prozyme.com for one source.