in-line vacuum degassing

[khw]

I am running two Agilent 1100 with quaternary pumps since 6 years. We started to observe some pressure spikes already a year ago, mainly with water/methanol 50/50. At that time we renewed the lines from the eluent bottles to the degasser and ultrasonicated water and methanol prior to using it. Now things again become worse and we even see in the tubings small bubbles, which, as we are afraid, can not be removed completely by the degasser.

My questions: What is the experience concerning the "life-time" of vacuum degassers? Is it allowed to have one empty channel or must all channels be filled with solvent? What maintainance can we do ourselves besides exchanging the whole chamber? Does replacing the tubings regularily (time frame?) help?

Thank you very much!

[Newman768]

Hello from Ludwigshafen

I have never seen inside a agilent in-line degasser, but what I knew from the Waters Alliance systems is that all chambers were connected to one vacuum pump.
If one camber filled with air, it is possible that this camber degresses the power of the vacuum pump. When you fill it with solvent you may notice better performance of the degasser.

About life time and/or changing tubes I don't have any hints.

[lcguy1]

Yoiu may want to check the frits in the mobile phase bottles. If you are sonicating the solvents before you put them on the system, you should not have any bubbles in your tubing. Make sure that the bottles are not tightly sealed also. The tubing in your degasser should last a long time. You can change the tubing inside, but it is not just a simple thing to do. As mentioned above, you should either plug the unused chamber, or put some mobile phase in it.

[Tim]

Are your degassers attached to the pump using the remote cable supplied by Agilent? If the degasser can't maintain a certain level of vacuum or has other problems that mean it is not working properly it will cause the pump and rest of the 1100 system to shutdown. Unfortunately, it doesn't tell you what is wrong - you have to work that out for yourself

Having air in the lines you are not using could cause problems. Try filling them with degassed methanol and putting screw-in caps on the ends of the degasser. If you need to keep them connected, purge the lines with degassed methanol and keep them in a bottle of it so the lines will always be full.

You could still have issues with the degasser itself. We have had to replace the vacuum chanbers and pumps in the past. It could also be an issue with the pressure sensor, since it may think it has a higher vacuum than is actually present.