ver.200603E
SHOWA DENKO K.K. (https://www.shodex.com/)
4
6.4 Column Cleaning
Problems in peak shapes and elution time changes or elevated column pressure etc. are often caused by
insoluble or adsorbing components present in the eluent and reagents being deposited inside the column. These
problems may be resolved by cleaning the column.
If a guard column is used with the analytical column, first remove the guard column and check the performance
of the analytical column alone. If the problem is solved, most likely the cause is from the guard column. In this
case, clean the guard column.
If the problem is not solved by removing the guard column, clean both guard and analytical columns. Make sure
to clean the guard and the analytical columns separately. When washing the column, let the washing solution
flow from the column outlet go directly into the waste container and not let the solution go through the detector.
<Cleaning Method>
(1) Insoluble components that block the column inlet may be removed by reversing the flow direction, i.e.,
introducing the eluent from the column outlet, with flow rate at less than half of the recommended flow rate.
(2) Follow below cleaning steps for adsorbing components. For an efficient cleaning, reverse the flow direction
and use the flow rate at 0.35 mL/min
Method 1: Adsorption of hydrophilic compounds
Washing Solution
Cleaning Time
1 H
2
O
25 min
2 100 mM KOH or NaOH aq. solution
100 min
3 H
2
O
25 min
4 Eluent
100 min
Method 2: Adsorption of hydrophobic compounds
Washing Solution
Cleaning Time
1 H
2
O
25 min
2 H
2
O/CH
3
CN = 95/5
20 min
3 CH
3
CN
100 min
4 H
2
O
50 min
5 Eluent
100 min
7. Column Storage
If preferred to store the column with the eluent used, remove the column from the system, securely tighten the
end caps and store the column in a refrigerator. Alternatively, if preferred to store the column at a room
temperature, replace the in-column solvent with the shipping solvent. Then, remove the column from the system,
securely tighten the end caps and store the column at a location with stable temperature (a cool and dark space
is recommended). Refer to section 6.3 Eluents for how to replace the eluent.
Attention!
· Never allow inside of the column to dry. It can damage the column.
· When replacing the in-column solvent with shipping solvent, detach the suppressor before
introducing the shipping solvent to the column.
· When reusing the column stored in a refrigerator, first wait for the column temperature to
be ambient, and then remove the end caps and install the column on the system.