1. First, remove the chromatographic column, connect the two-way valve, open the drain valve, and rinse the four channels A, B, C and D with warm water in turn (it should be filtered before heating at 40~50C, and it can be directly put into a beaker for easy access), with a flow rate of 5ml/min, and the time of each channel is about 5~ 10min.

2. Secondly, close the drain valve, set the flow rates of the four channels A, B, C and D to 25% respectively, appropriately increase the total flow rate within the pressure range that the system can withstand, and rinse with warm water for 20~30min. During the flushing process, the plunger rod part of the pump head can be slowly flushed with warm water to remove the salt that may be deposited on the plunger. After washing with warm water, keep the flow rate of the four channels constant and wash with methanol for 20 ~ 30 minutes.

3. Finally, after methanol cleaning, keep the flow rate of the four channels unchanged, and clean with filtered isopropanol for 20-30 minutes. Pay attention to the flow rate when flushing, so as not to damage the instrument due to excessive pressure. 6. After washing with isopropanol, keep the flow rates of the four channels constant, and wash with methanol (or eye B depends on the storage conditions of the chromatographic column required by the project) for 20~30min. After washing, turn off the machine.