Leak in HPLC system

[mike2333]

Hello,

we have a aglient 1100 HPLC which was not used since about 1/2 year. Now I'm triing to purge the HPLC. The IN-flow has no bubbles. But the OUT-flow has always in a constant regularity some bubbles.

I think there is a leak in the system. I'm not a expert in HPLC, do you have some advices: how to get the system bubble-free.

Thanks for your help,

Mike

[Consumer Products Guy]

The IN-flow has no bubbles. But the OUT-flow has always in a constant regularity some bubbles.

1. Are you using a degasser?

2. Do you see such bubbles coming out the clear tubing of the purge valve? I would close the purge valve, disconnect the tubing at the column, place the tube in a beaker of methanol, and run each channel at 5ml/min, see if you see bubbles there.

3. When such 5ml/min flow is going, the fluid should stream out steady from the tubing as well, no pulsations. The pressure for each channel should be under 10 bar at 5ml/min; if an aqueous channel is over 10 bar, time to replace the PTFE purge frit in the purge valve.

Then report back.

[mike2333]

Hi,
I thought every kind of HPLC is having a degaser.
Since I am not an expert in HPLC, I thought our System (Aglient 1100) is automatically degasing the solvents.
How can I manually control the degaser?

[lmh]

if the bubbles are in the clear tubing coming out of the purge valve, don't panic. You can get bubbles in there when actually there is no air in the system at all (I'm not sure how). Try pumping at normal flow through a column and see if the pressure saw-tooths up and down; if it doesn't, you probably don't have any bubbles in the pump.

[Consumer Products Guy]

Hi,
I thought every kind of HPLC is having a degaser.
Since I am not an expert in HPLC, I thought our System (Aglient 1100) is automatically degasing the solvents.

Assume that "modern" HPLC is 4 decades old. We got our first system with a degasser in early 1980s, an HP/Agilent one that used heat and stirring (and maybe some vacuum) to degas. Our next system used helium sparging to degas. Later vacuum degassing using permeable tubing was developed.

Vacuum filtration, ultrasonic mixing were also used in the old days to degas solvents.

[lmh]

You know if an Agilent 1100 system has a degasser because it's a flat module usually placed just below the solvent tray, and the tubes from the solvent bottles go into it, and come out again to go to the pump. If there is nothing in the flow-path between the pump and the bottles, there is no degasser.
It would be normal for an 1100 system to have a degasser, but there's nothing to stop someone insisting on buying a system without one.
I am not sure if you can control the degasser manually. You shouldn't need to: it is just there and does its job, and occasionally lights up its led in red if something goes wrong.
A failed degasser will not create bubbles after the purge valve when there are no bubbles before. If there is dissolved gas, it can only come out of solution when pressure decreases. When you are purging, your system pressure should be almost nothing, so there is no chance of a pressure-drop across the purge valve, so no dissolved gas should come out. The bubbles in the line coming from the purge valve are something else, probably an indication that air can get into Agilent purge-valves when they're open.

[mike2333]

Thanks a lot for your help!

It seems like there was a problem with the purge button (so that it seemed like there was always air in the system.)

Cheers