1. It is better to use pre-column to protect the flash column, 2. Every time clean the flash column after the analysis is finished. If there are no acid, base or salt in the mobile phase, it is suggested to wash with 90% methyl alcohol for 30 to 60 minutes. On the contrary, you should firstly use 10% methyl alcohol to wash for about 1 hour, and then use multiple pumps to wash with 90% methyl alcohol for 30 to 60 minutes. Repeat the process several times if necessary, this can properly reduce time. If the flash column is not used for a long time, it should be sealed up by pure methyl alcohol or acetonitrile after cleaned up, 3. If there is an ion-pairing agent in the mobile phase, you should wash the flash column more carefully and not for analysis of other substances, 4. Try best to avoid bounce-back, unless the manufacturer clearly permit to do that, 5. The ordinary gas capillary flash column should not be used under the temperature above 40 ℃, 6. Check the column efficiency at regular intervals. If there is a decline, wash the flash column with 10% isopropanol methanol or methylene dichloride to improve efficiency.