High Performance Liquid Chromatography - How to troubleshoot minor faults?
2024.09.12
[1] The pump pressure fluctuates, with a fluctuation range of about 10 bar. . . . . .
Solution: 1. The original white head was a bit dirty, and the problem was not solved after replacement; 2. After removing the valve core from the active valve, similar bubbles were found. It was immersed in methanol-water solution for 5 minutes to try to remove the bubbles. After reinstalling it and observing it again, it was still not solved; 3. After replacing the new valve core and installing it, there was no more jumping. After observing for a period of time, it was relatively stable and successfully solved.
[2] Fault: ① plug homing over pressure ② There was no pressure and no liquid outflow during perfusion and setting flow rate ③ The detector shutter could not be reset ④ After the high concentration sample was introduced, the corresponding position of the blank also produced a peak. . . . . . .
Possible reasons: ① The online filter is blocked ② The check valve under the pump head is blocked ③ The detection pool may be dirty, or the light path may be a little blocked. If that doesn't work, it may be that the lamp has reached the end of its life ④ The small rag is dirty and needs to be replaced
Solution: ① Remove the online filter, put it in a beaker, add purified water and boil it for 5-10 minutes, then supersonicate with methanol. If it is still blocked, soak it in dilute nitric acid. If it still doesn't work, replace it with a new one. This is a consumable. ② Remove the one-way valve under the pump head. Both may be blocked. When it is just removed, you can't hear any sound when you shake it vertically next to your ear. Simply blow the one-way valve with an ear-washing bulb (pay attention to the direction). If there is no response after blowing, you can use a solvent to ultrasonicate it, but don't boil it in water. Generally, it will not affect the experiment if you can hear the sound when you shake it next to your ear. ③ First flush the detection pool with a solvent. What to use depends on the specific sample; if it still doesn't work after flushing, remove the detection pool and check the lamp energy. If the energy is OK (there are several thousand), you may have to clean the optical path. For the first cleaning, it is recommended to call an engineer, because the part to be cleaned is at the bottom of the detector. There is a black piece with a seam in the middle, and the screws of that piece are all octagonal, which is very troublesome to remove. ④ Take out all 5 sample trays. You can see a black protrusion inside (use a flashlight to see it clearly). The injection needle usually draws samples from that place. You can remove it by reaching in. There is a small white circle inside (it will turn black naturally after being used too much). Just replace it with a new one. Usually 10 are provided when you buy the instrument.
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