Chromatography Forum

Hi,
I am experiencing some high pressure issues with our Agilent 1100 hplc. Normal equilibration pressures at 1.5 ml/min are consistent at around 120 bar. Now, equilibration pressure at 1.5 ml/min are +200 bar.
What I have tried:
Removed column, flow to waste, low- no pressure observed.
Flushed column forward and reverse w different solvents. No relief of high pressure.
New mobile phases, completely flushed system. No relief of high pressure.
Installed a brand new column, observed same high pressure.

I am having trouble locating the problem and think it may be in the pump. Any help is appreciated from the community. Thank you all.

Am I understanding you correctly?

You disconnected the column and replaced it with a union, then ran your mobile phase at your usual flow-rate of 1.5 mL and there was low pressure? OR did you disconnect the column, and not connect the tubing to a union, but just had it go directly into the waste?

If you connected a union in place of the column, then this suggests it is the column.

So It's not the column, not the tubings, sounds like a clogged frit in the purge valve.

Replace the PTFE frit ($5) inside the prime purge valve. You are supposed to be rinsing the valve and replacing this important frit every 1 month as part of normal maintenance.

If removing the column, union or no union, drops the pressure you can safely eliminate pump and sampler has problem areas.. My guess would be column..

The whole flushing columns backwards and forwards has never really been my favorite procedure and rarely has recovered a column to good conditions again..