The back pressure of the column is higher than when it was used previously.
->Make sure that the column is stored according to the instructions in the manual.
->Please check that the mobile phase containing salt such as buffer solution is not flowing immediately after connecting to the equipment.
->Salt may precipitate and the column may be clogged. If precipitation of salt is suspected, slowly pass a solvent with high elution power such as pure water and try to improve. If the problem is not resolved, please replace the column to new one.