Chromatography Forum

Dear all,

I'm going to use LC column Nucleosil 100-5 SA in the next days. I don't have any experience with this kind of stationary phase and I have some doubts about:

1. When the column is supplied in 0.15 M (NH4)2HPO4 (the vendor notice) is the appropriate eluent for the first activation should be the same?
2. What is the appropriate eluent for the long-term storage? Is it 0.15 M (NH4)2HPO4 again?
3. My working mobile phase consists below 2 % organic solvent and the aqueous buffer is the main content. Should I after use wash the column with the same proportion of organic/water?

Thank you in advance!

1. When the column is supplied in 0.15 M (NH4)2HPO4 (the vendor notice) is the appropriate eluent for the first activation should be the same?

Silica-based HPLC ion-exchange columns generally have a low capacity, so "activation" is not usually required. You simply equilibrate the column with your mobile phase. If your mobile phase is based on a more weakly-bound ion than HPO4= (Cl-, for example), then equilibration may take a long time.

2. What is the appropriate eluent for the long-term storage? Is it 0.15 M (NH4)2HPO4 again?

Whatever Machery-Nagel recommends! That said, I have been known to simply store columns in the mobile phase. That can shorten the lifetime, but saves on equilibration time at the next use.

3. My working mobile phase consists below 2 % organic solvent and the aqueous buffer is the main content. Should I after use wash the column with the same proportion of organic/water?

Per the above comment, without knowing the details about your mobile phase and the equilibration time, it's hard to give a specific answer. In general, some organic solvent in the mobile phase is a good thing as it tends to inhibit bacterial growth.

By the way, if MN recommend anything different from what I have said, follow their advice!