Solvent Degassing Considerations - Waters ACQUITY Refractive Index Detector Overview And Maintenance Manual

2 Preparing the detector
Vacuum degassing can possibly change the composition of mixed
Note:
solvents.
Sonication
Sonication with high-energy sound waves drives energy into the solvent and
causes the submicron-sized "bubbles" of gas to aggregate. As the gas bubbles
aggregate, they become large enough to float out of the solvent and dissipate.
Sonication alone degasses 4 liters of solvent in approximately 20 minutes.

Solvent degassing considerations

Select the most efficient degassing operation for the application.
Vacuum degassing
The longer a solvent is exposed to vacuum, the more dissolved gases are
removed. Two factors affect the amount of time the solvent is exposed to the
vacuum.
Factors affecting time solvent is exposed to the vacuum:
Factor
Flow rate
Surface area of the
degassing
membrane
Sonication plus vacuum
Sonication combined with vacuum degasses solvent very quickly. This
technique is less likely to change the composition of mixed solvents because
the mixed solvents are held under vacuum for only a short time (less than a
minute is usually sufficient).
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Effect
At low flow rates, most of the dissolved gas is
removed as the solvent passes through the
vacuum chamber. At higher flow rates, lesser
amounts of gas per unit volume of solvent are
removed
The length of the degassing membrane is fixed
in each vacuum chamber. To increase the length
of membrane, you can connect two or more
vacuum chambers in series.