ver.220208E
SHOWA DENKO K.K. (https://www.shodex.com/)
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7.4 Column Cleaning
Problems in peak shapes and elution timing 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 less than 3.0 mL/min. Introduce 5 to 10 times column volume of the washing solvent.
Method 1: Adsorption of hydrophilic compounds (when using aqueous eluent)
Introduce the eluent with a high polar organic solvent (acetonitrile or methanol) added.
Method 2: Adsorption of ionic compounds
Introduce the eluent with a higher salt concentration.
Attention!
· Keep the organic solvent and salt within the concentrations stated in 4.2 Usable Solvents.
8. Column Storage
Remove the column from the system after replacing the in-column solvent with the shipping solvent. 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 7.3 Solvent Exchange for how to replace the eluent.
Attention!
· Never allow inside of the column to dry. It can damage the column.
9. Column Inspection
Inspection method is described in the Certificate of Analysis (CoA).
Theoretical Plate Number (N) and Asymmetry Factor (Fas) were calculated using the below equations.
(1) Theoretical Plate Number (N)
(2) Asymmetry Factor (Fas)
