UTMI
1. Prevent any solid particles from entering the infusion pump body, because dust or any other impurities will wear the plunger, sealing ring, cylinder and one-way valve, so any solid particles in the mobile phase should be removed in advance. The mobile phase is best distilled in a glass container, and the common method is filtration, which can be filtered by Millipore filter membrane (0.2um or 0.45um). The inlet of the pump should be connected to the sand filter rod (or sheet), and the filter of the infusion pump should be replaced frequently.
2. The mobile phase should not contain any corrosive substances, and the mobile phase containing buffer should not remain in the pump, especially if the pump is stopped overnight or for a long time. If the mobile phase containing the buffer is left in the pump, due to evaporation or leakage, or even simply due to the quiescence of the solution, it is possible to precipitate tiny crystals of salt, which will damage the seal ring, plunger, etc. like the solid particles mentioned above. Therefore, it must be pumped into pure water for thorough cleaning, and then replaced with a solvent suitable for column preservation and pump maintenance (for reversed-phase bonded stationary phases, it can be methanol or methanol and water).
3. When the infusion pump is working, be careful to prevent the mobile phase in the solvent bottle from running out, otherwise the empty pump will also wear the plunger, the sealing ring or the cylinder body, which will eventually cause liquid leakage.
4. The working pressure of the infusion pump should not exceed the specified maximum pressure, otherwise the high-pressure sealing ring will be deformed and liquid leakage will occur.
5. The flow box should be degassed first to avoid bubbles in the pump and affect the stability of the flow. If there are a lot of bubbles, the pump will not work.
If the infusion pump fails, it is necessary to find out the cause and take corresponding measures to eliminate the failure:
1. There is no flow of mobile phase and no pressure indication. The reason may be that there is a lot of gas in the infusion pump. At this time, the pressure relief valve can be opened to make the pump run at a large flow rate (5ml/min) to exhaust the air bubbles. A 50ml syringe can also be used at the pump outlet to help. Extract the gas. Another reason could be that the sealing ring is worn and needs to be replaced.
2. The pressure flow is unstable. The reason may be air bubbles that need to be removed, or there is foreign matter in the one-way valve, you can remove the one-way valve, immerse it in acetone, and perform ultrasonic cleaning. Sometimes there may be air bubbles in the sand filter rod or it is partially blocked by the tiny crystal grains of salt or the microbial growth. Dilute acid (such as 4mol/L nitric acid) to quickly remove microorganisms or dissolve salt, and then wash immediately.
3. The reason for the high pressure is that the pipeline is blocked and needs to be removed or cleaned. The reason for the drop in pressure may be a leak in the line. Checking for blockages or leaks can be done segment by segment.
