Recently I noticed that air bubbles constantly appeared from my pump and keep clogging my columns.
【Solvents】
- Solvent A =sodium acetate buffer (0.05 M, pH 6.0) in water containing 5 mM β-CD (Sigma-Aldrich, UK)
- Solvent B=sodium acetate buffer (0.1 M, pH 6.0 anhydrous) in a water:methanol: acetone mixture (volume ratio 20:72:8).
【degas and filter situation】
- Because of the degasser damage, I only ultrasonic degassed my solvents for 20 mins.
- filtered properly
【Issue】
When each solvent went through the single channel, there were no air bubbles (e.g. Flow 1.2 channel A 100%). However, when I chose 80%A+20%B, Flow 1.2, it generates tiny air bubbles. Please see the photo I took.
【potential answer】
1. solvent is still not enough degassed
2. the piston or seal in the pump was worn
The tube seems to channel the mobile phase to the pump but not after the pump. I have experience that the degasser was damaged but it is usually not possible to check because most tubes are opaque. I believe the bubbles appeared could be present in the mobile phase itself. The only way now it to make sure your mobile phase is free from dissolved gas, especially those containing high portions of water. Some bubbles may be generated from the suction filter head dipping in the mobile phase. You may need to remove and sonicate it. That could help to reduce air bubble generation.
If your problem is to exit the air bubbles, you can wash many time and they will exit but you should know the reason for this problem. Check your degasser, check your mobile phase itself and do a good sonication for it.
If the problem is in your degasser and your method is isocratic, you can mix them in an one bottle and sonicate them together then make your HPLC use single line.
Choon Fu Goh Thanks for the answer. Actually, I just cleaned the filter with Nitric acid and HPLC water. The reason why I highly suspect it was the pump or the insufficient degas issue, is the air bubble only generated when HPLC pump did mixing. Baed on your experience, the 20mins sonication is enough if I get rid of the degasser machine?
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