Chromatography Forum

Hello,

I've been seeing conflicting information regarding the storage of IEX columns (SCX, SAX, WCX, etc). Recently, I've seen recommend storage in methanol, while others recommend sodium azide (highly toxic). I'd rather not have to use the Na Azide. Anyone have a definitive storage solvent?

The storage solvent, in your observation of the recommendations, is probably dependant on the matrix for the IEX particles. Some can take organic and other can't. The main purpose of the methanol and sodium azide is to prevent microbial growth.

You should follow the manufacturers recomendation in all cases.

Thanks. Makes sense. I recently stored a column per the insert and it took a hit in Rs. Later they sent an addendum specifically instructing NOT to use MeOH (which the insert told me to do), and to use 20% ACN. Reconditioning the column restored the Rs measurements to its orignal value.

Just as an addition.

Using methanol versus sodium azide really does not make a big difference. Methanol is also highly toxic and there you need 25 to 100%. While sodium azide is used around 0.02%.
We just forget about the methanol toxicity dur to the fact that we need to use it so often.