Pressure go zero

[tonja79]

Hi at all,

I have another problem with my HPLC that I can't understand.
When I turn on the HPLC monday or when I leave my HPLC turn off for 2 or 3 days when the gradient go to 70% of MeCN break down the pressure and to return to the normal situation of pressure I have to open the purge valve and turn off the pump and follow turn on for many times until the pressure when I close the purge valve is normal. I think that there is some air balls thet I must flow out.

My HPLC is a Agilent 1200 with quaternary pump, degasser and DAD.

Thank

PS: This forum is fantastic

[Jackus]

The best practice is to flush pump before work.
Open purge valve and flush the pump at high flowrate (5ml per minute). There may be bubble inside pump chambers, outlet ball valve or somewhere in system .

[Bryan Evans]

If you think that you have bubbles in the line - then yes you should purge your system out.

For the quat pump - Put all 4 lines in 60:40 H2O:ACN - set the pump to 25:25:25:25 A:B:C: D - and let the instrument pump at 5mL/min for 10 min (purge valve open).

Then you can reduce flow rate to 1 mL/min, close the purge valve, and continue pumping for 30 min (no column).

[S.M.PANDYA]

Hi Tonja

Yes it is based on unknown operational mistakes . Normal practice is that HPLC while putting off , it should be flushed with suitable solvent initially by opening drain valve . After ensuring no bubble is there in suction line , washing of suitable solvent is continue up to desired satisfaction level .
The same can be repeated when again HPLC work is to be started .

Simultaneously analyst or operator must ensure cleaning of filters frequently .

Degasser of HPLC system also should work properly so that no excess gas remains inside the solvent & creates bubbles later .

It should also be ensured that there is no leakage in suction line or leakage should not be ignored .