Chromatography Forum

Hello everybody.

A rookie question. I'm going on vacation and leave my HPLC for approx. 3-4 weeks. Would that be enough to pump the whole system with ACN and seal the end fitting of the column (C18)?

I tend to store C18 columns in 80% acetonitrile or methanol, the remainder being water with no acid or buffer. For other columns, follow the manufacturer's instructions. I don't use 100% acetonitrile because if the column has ever been in contact with anything slightly salty, if any trace of salt remains, there is just a slight danger it might gradually precipitate. This is probably just an unreasonable worry as it should have been washed!

As for the hplc system, most systems can be stored in almost anything for a month, provided it's not too corrosive. I've heard 50% isopropanol suggested. I would use anything acid-free and with sufficient organic content to prevent algal growth. If you have lines that have been used in buffers, I would not store their inlet filters in 100% organic; we had dire problems some years ago with Waters Alliances used with ion exchange when the inlet filters, even after extensive flushing, were put in 100% acetonitrile or methanol. I am guessing, but think that during flushing, most of the water takes the easiest route through the filter, and traces of salt remain in the less accessible depths of the filter. On soaking for longer periods in organic solvent, it migrates out and precipitates, and the result is unreliable check valves.

lmh, thank you for your advice!
I add only formic acid to my mobile phases, and the column manufacturer (Varian) recommends to store in 100% MeOH or ACN, so ACN should be OK.

Some HPLCs have problems with check valves getting sticky when stored in 100% acetonitrile, thus it is recommended to use methanol, but it depends on the HPLC system.

Some HPLCs have problems with check valves getting sticky when stored in 100% acetonitrile, thus it is recommended to use methanol, but it depends on the HPLC system.

Thank you for your response, I do use Agilent 1200

Finally I've started the HPLC, everything seems to be Ok, thanks to everybody.