All-
I'm beginning development on a SEC method for a certain polysaccharide (Mw > 100kD)using a PMMA column. Can anyone explain to me how the addition of a salt (sodium nitrate or potassium phosphate, 0.1M)might affect my chromatography and which would be more appropriate to use?

Thanks,
Jeff

Jeff,

Your questions is reasonable but I think mostly salts help to keep your compound happy in the solution rather than helping for your chrmotography. Specially SEC is based on a purely molecular sieving mechanism, salts and buffers may not directly helping to elute the compounds but in method development resolution, specificity, and sensivity depend on the ionic strength of various salts/buffers. SO in SEC you may have to try a couple of high and low ionic strength buffers.

Good Luck!

Ananada

Of the ions involved, sodium, potassium and phosphate are all known to form weak complexes with polysaccharides. Nitrate, on the other hand, has no known complex. If you are interested in increasing the ionic strength with a minimum effect on the effective net charge of the polysaccharide, I would say the sodium nitrate salt is a better choice.

Ananda and Chris-

Thanks for your advice and info.

-Jeff