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(6) Stop the pump, lift the inlet tube out of the container, and use water to wash
off any buffer adhering to the outside of the tube.
(7) Insert the inlet tube into a container filled with water (use a different container
than that used in Step 2 above) and restart the pump. The solvent up to the
purge valve is thus replaced.
(8) Close the purge valve.
(9) Verify that solvent is flowing out of the tube attached to the pump outlet port
without interruption.
(10) While continuing to pump, lift the inlet tube out of the water, take in 3 ~ 5 ml of
air (bubble), and reinsert the inlet tube into the water.
(11) The air bubble will be taken up into the pump and discharged from the pump
outlet port. Make sure that water continues to flow from the pump outlet port
without interruption. The solvent in the pump is thus replaced.
4.2.3 Replacing the water with methanol
In the procedures described in Section 4.2.2, substitute the word "buffer" for "water"
and the word "water" for "methanol", and then repeat the procedure using water and
methanol rather than buffer and water.
4.2.4 Notes on solvent replacement
When replacing solvents always be sure that the solvents are intermiscible at any
ratio. Figure 4.4 lists the solubility of various solvents that are commonly used in
liquid chromatography.
Note: Acetone has a low viscosity and a strong dissolving power for many
compounds and is therefore an effective substitute for ethanol and
isopropanol. However, since acetone has a high absorption in the UV region,
the UV detector will be affected if replacement is not performed sufficiently.