Chromatography Forum

Hello

What would be the procedure if I wanted to change the composition of the mobile phase used in the HPLC column if I have a buffer and methanol and want to change to a phase with another buffer and nitrile?

I was thinking of first washing the column with a 90:10 water (without buffer):methanol ratio and then adding the new mobile phase. I was wondering if I should include extra steps, such as washing the column first with the new phase but without buffer and then with buffer.

Here is how we do:

1. Rinse the frits which were in contact with the previous mobile phases 2-3 times with the new mobile phases. We usually use a small (e.g. 25 mL), clean cylinder for that.
2. Prime both lines with the new mobile phases still in the small cylinders for 0.5 or 1 min.
3. Prime both lines with the new mobile phases in the bottles for 4-5 min.
4. Flush the column with the new mobile phases. We usually use 50/50 but some can have other preferences.

The most important is not to contaminate the new mobile phases with the old ones. Your column is supposed to be stored in an organic solvent without buffer, so there should be no risk of precipitation.