I am using a VanGuard pre-column (2.1 mm ID x 5 mm length) that I had to uncouple from a C18 BEH column as the pressure was getting too high.
How can I clean the pre-column ? I first thought of back flushing and maybe sonicating in MeOH or ACN. Any better suggestions ?
Cheers. Pierre
HI Pierre
have you tried to remove the filter of the pre-column? sometimes this is the reason for the overpressure
In any case ACN 100% or MeOH should work
You may indeed back flush using isopropanol which is stronger solvent than MeOH, but the aim of a pre-column is also to be sacrificied to save the column.
Most pre-columns are designed to either be disposable or have internal disposable filters that need to be periodically replaced. Backflushing may help but if not then the simplest option is to remove the filter but you then risk the column. Personally I would order a replacement guard column as from the sounds of it, it has done its job and prevented your column getting blocked. Then all you need to decide upon is if you time waiting for the replacement is worth more than the risk to your column.
Many thanks for your valuable answers. I will certainly change the entire pre-column asap as this model does not have a cartridge.
Hi Pierre,
Removing and replacing filters in Waters (guard) columns is risky. Usually I backflush with isopropanol followed by hexane and back to isopropanol at 60-90 °C. You can also apply "shocks" to the guard by changing abruptly from water 95% to ACN 100% several times, which sometimes helps. If none of these attempts works, just give it away and replace with a new one.
Hi,
remove the frit of the guard column & sonicate whole guard column assembly in 5% H2SO4 for 15-20min then sonicate in 100% water to remove acid and then with 100% methanol. Pressure will definitely get reduce.
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