Air bubble in HPLC Pump

[sboopathi]

We are using Agilent 1200 SL series with binary pump without an degasser. After degassing by ultrasonicator for 15 minutes, we are using the mobile phase, but still produces air bubble in the pump especially the problems comes only in pump B. Sometimes the bubble comes from pump to the solvent. Because of the air bubble, there is a drift in retention time. We dont have enough resource to buy an degasser right now. Can you please suggest me how to avoid air bubble in the pump and how to remove the air bubble present in the pump.

[Gerhard Kratz]

First of all please clean the inlet frit of your solvent connected to pump B. Than disconnect your column and guard column and purge your HPLC system with an organic solvent. That should eliminate the air in your HPLC system. After ultrasonic of your mobile phase you can put nitrogen into the bottles with your solvents, but be careful, it does not mean to put pressure on the mobile phase. If one of your solvents is 100% water you can heat it up while ultrasonic. That will help also. Good luck.

[lmh]

what are the solvents on the A and B sides of your pump? If you swap them over, does the problem remain on "B", or does it go with the solvent.

On the subject of degassing by ultrasonication: I have no doubt it can work, but it depends on the way you sonicate. Many years ago I worked in a lab who put their solvents in a simple ultrasonic waterbath for 30min, in an open lab full of people. The noise so irritated us that we decided to test it. We had a portable dissolved oxygen monitor. We checked the aqueous buffer at the start: 100% saturation. We checked 30 minutes later. 99% saturation. Sonication doesn't get rid of all gases every time, depending on how it's done... there is mythology in action here.

[lmh]

... putting the aqueous buffer in a side-arm flask with a magnetic stirrer and applying a vacuum while stirring reduced dissolved oxygen, as I remember we hit about 10% after only a 1 minute treatment.

[tom jupille]

Several comments here:

First of all, I'm not sure that replacing air with nitrogen does anything as far as bubble formation is concerned (air is, after all, mostly nitrogen).

Vacuum degassing (with or without sonication) is, in fact, moderately effective, but it is a "one shot" technique; as soon as you take off the vacuum, the solvent beins to re-equilibrate with the atmosphere.

As for any bubbles *in* the pump, the 1200 should have a "prime-purge" sequence for just that problem.

[Consumer Products Guy]

We are using Agilent 1200 SL series with binary pump without an degasser.

False economy.

[lmh]

one-shot... absolutely! The moment you stop degassing, gas starts to get back in. Given the world's dwindling supplies of helium, it seems wrong to me to use helium to fill the bottle's head-space. Degassers are worth it; any chance of finding a second-hand stand-alone degasser from somewhere?

[carlos.teixeira]

Your degassing time is too long; flux Isopropanol on your B channel before using; convince your Number One to approve the purchase of a degasser since time is money. Have great eluting!