There are bubbles in the mobile phase, the pump is turned off, the pressure relief valve is opened, the purge button is turned on, the degas is cleaned, the bubbles are continuously ejected from the HPLC column, and the mobile phase enters the mobile phase. No matter how many times the purge button is turned on, the continuously generated bubbles cannot be removed.
Syringe filter is immersed in a buffer such as ammonium acetate for a long time. The inside of the filter grows due to the growth of mold, forming a cluster of bacteria, blocking the filter. The buffer is difficult to smoothly pass through the HPLC column, and the air enters the mobile phase through the filter under the pressure of the pump.
The treatment filter is immersed in a 5% nitric acid solution and ultrasonically cleaned for a few minutes. The filter can also be immersed in a 5% nitric acid solution for 12 to 36 hours, gently vortexed several times, and then the filter is washed several times with pure water. Open the pressure relief valve, open the purge button to clean the degassing.
If there are still bubbles emerging from the HPLC column continue to soak the filter in a 5% nitric acid solution. If there are no bubbles, the filter will emerge from the filter. The internal mold flora has been destroyed by nitric acid and the mobile phase can pass through the filter smoothly. Open the pressure relief valve, turn on the pump, adjust the flow rate to 1.0 ~ 3.0ml / min, rinse the filter with pure water for about 1 hour. The filter can be cleaned. Close the pressure relief valve and rinse with pure methanol for half an hour.
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