The impact of bubbles on HPLC
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What are the factors that affect HPLC detection by bubbles? What measures should be taken to remedy the situation if bubbles enter the HPLC?
This can lead to high pressure before the column, preventing the flow phase from passing through. A 100 ml syringe can be connected to the outlet of the flow phase to extract air, thereby removing the bubbles
What if it flows into the detector along with the mobile phase? What negative consequences will arise? Will it cause any damage to the detector? Also, what should be done about the bubbles that enter the detector?
1. It is necessary to pay attention to the causes of bubble formation, which generally stem from three sources: first, the storage tank for the mobile phase (being dirty or having a dirty filter); second, leaks in the plunger gasket; third, loose connections. 2. The apparent phenomenon is unstable column pressure, meaning that the bubbles change under the influence of pressure and friction along the flow path. 3. This does not cause any damage to the detector, but it makes it practically impossible to conduct analyses
Poor degassing of the mobile phase is a major cause of bubble formation. If bubbles are present, remove the column first and flush the pump and detector with high flow rates. If bubbles have entered the column, be careful regarding the column’s capacity when performing the flushing process
Why can’t we make a sample? Unstable pressure will only cause instability in the baseline, right? Does it have any significant impact on sample analysis? When manual sampling was first attempted, small bubbles would always be drawn into the sampler (we used 1 ml disposable syringes for sampling); there were also tiny bubbles at the connection between the filter tip and the needle. It seemed that these bubbles might enter the instrument along with the sample solution, causing various problems.
After the pressure becomes unstable, the baseline fluctuates, and at the same time your qualitative and quantitative criteria will shift
1. The most noticeable change caused by bubbles is unstable pressure with large fluctuations. 2. Whether it is possible to use a syringe to draw air at the outlet of the mobile phase depends on the model of the online degasser; drawing air blindly should be avoided, as this may damage the instrument. 3. Defoaming should be done first, so that the mobile phase does not pass through the chromatography column; increasing the flow rate can help to remove the bubbles