Operation Manual Shodex Asahipak GF-HQ series Version 2106029E
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provide linear calibration curves over a set molecular weight range. If a GF-7M HQ was used together
with columns with different pore sizes, this changes the mixing ratio of the gels and consequently it
may deform the linear calibration curve.
Caution! • Verify that there is no solvent leak. It may cause electronic leakage, rust, and/or
chemical injury.
Attention! • Make sure not to let air bubbles enter the column while installing the column. The
air bubbles may damage the column.
• When restarting the system after column installation or after holding the eluent
flow, start the system at less than 0.2 mL/min. A rapid increase in pressure can damage
the column.
• If the column was used at an elevated temperature, lower the flow rate to less than
0.2 mL/min at the end of analysis. Then, turn off the column oven, and let the column
temperature return to room temperature before stopping the pump. If the pump was
stopped while the eluent inside the column was still hot, as the eluent temperature
decreases, its volume also decreases. This may result in creating an empty space in the
column and deteriorates the column.
Note • It is recommended to set the pump limiter to avoid exceeding the maximum
pressure.
7.3. Solvent Exchange
(1) When replacing the solvent, start the system at less than 0.2 ml/min. Recommended solvent
volume to introduce at each step is 3 to 5 limes of the column volume.
(2) Check miscibility/solubility of the desired new solvent and the solvent currently filled in the column.
(3) When replacing water with an organic solvent, first introduce methanol, and then replace it with
the new solvent. When replacing an organic solvent with water, first introduce methanol, and then
replace it with water.
(4) When replacing aqueous solution of salt with an organic solvent, first introduce water at the flow
rate at half of the recommended flow rate for 30 minutes. Follow step above (3), and then replace it
to the new solvent. When replacing organic solvent with aqueous solution of salt, replace with the
reverse procedure.
(5) When replacing an organic solvent with another organic solvent, introduce the new solvent directly.
(6) When replacing the current solvent with a solvent with low miscibility/solubility to the current
solvent, first use a solvent that is miscible/soluble to both eluents, and then replace it with the new
solvent.
e.g. When replacing water to hexane, first run methanol and acetone in that order, and then introduce
hexane.
e.g. When replacing THF to DMF with LiBr, first run DMF, and then introduce DMF with LiBr.
Attention! •Frequent solvent replacement deteriorates the column, and thus not recommended.
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