Chromatography Forum

Sorry if asked before!


I have luna C18(2) column 150 x 2mm. Because I share the LC system with other people, So I have to took off the column (store in 100% ACN) after my run. The problem is that everytime I put my column on after couple days (other people use the system), I got high pressure!
My mobile pahse: 0.1% acetic acid; ACN.
But if leave the column on and next day I have no problem to run it. I do wash the system (other people use MeH and water without buffer) before I install the column, but still no good!
So, I have to wash my column quite long time (at least 3 h) at 0.1 ml/min before I convert to 0.2 ml/min. As long as it runs the retention time is good and peak is sharp. What is wrong?

It probably has to do with the fact that your column is stored in 100% ACN. Whoever is on the system before you is leaving a high concentraion buffer in the system. When the ACN hits the buffer post column, it precipitates some of the buffer and you get high pressure. Try rinsing the system with your MP prior to attaching your column.

To prevent the problem -
Run several column volumes of Your MP (0.1% HoAC/ACN) through the system Before you install the column. Going from atraight ACN to 0.1%HoAC in ACN shouldn't cause much of a pressure change. This keeps you from having to pump someone else's wash through your column.

Might want to purge the autosampler while your at it.

thank you guys! I definitely will try your suggestions next time!