Sephadex LH-20

[Luca]

I need to separate a compund that hydrolises in contact with water. For this reason my attempts with RP C18 colums were unsuccesful. I need to find a chomatographic method which does not use water as eluent.
Normal phase silica chromatography is not an option since my compound is very polar and wouldn't move. Gel filtration alone would be difficult since my byproducts have similar molecular weight.
I am going to try with Sephadex LH-20. Any tip on how to choose the best eluent? Or any suggestion for an alternative stationary phase?

Thanks in advance!

[Kostas Petritis]

Is your sample ionic/ionisable? Does you compound hydrolyse even with small amounts of water in the mobile phase (i.e. can you use HILIC?).

[MG]

I wonder if HILIC would work with only acetonitrile and methanol? It would be an interesting experiment.

There's also J. Chromatogr. A, 836 (1999) 235-244, where mixtures of hexane, IPA, and ethylene glycol are used to chromatograph polar compounds on silica.

[josebenjamin]

Dear Luca,

if your compound is so polar and reactive that decomposes quickly with water, then I would consider two alternatives.

First Derivatization. Many functional groups can be derivatized to make molecules more stable, more volatile, or make them more suitable for detection. The other option is GC with or without derivatization. Unless your molecule is much too high in MW, the chance is that it could be suitable handled by GC.

HILIC and Normal Phase could also be used, but it is not possible to say anything unless the structure is known. There is also non-aqueous RP, but your molecule may not be soluble in the required solvents (100% ACN for example), or the retention may be too short on most columns.

Good Luck

josebenjamin