Waters 600e User Manual page 247

Heat
Heating to remove dissolved gas is usually not effective unless you boil the eluent, and
this is not practical for mixed eluents. However, low levels of heat will raise the partial
pressure of the eluent and thereby reduce the rate of resolubilization of a gas. This may
affect the separation on the column.
Sonication
Sonication plus vacuum will degas eluent very quickly. This technique will not change the
composition of mixed eluents appreciably.
Caution: It is dangerous to apply vacuum to the brown gallon bottles in which eluent is
shipped. There is a high risk of implosion under these conditions.
Conclusions
With any of the above techniques, except sparging, the eluent will reequilibrate to air
saturation in 12 to 24 hours (depending on the eluent).
Degassing by vacuum or sonication is often performed for improved pump performance in
high-pressure applications. However, degassing may not yield the required baseline
stability for high-sensitivity absorbance detection. The most practical degassing method
for most applications is sparging. Due to the low solubility of the sparging gasses,
sparging will not impair pump performance in most eluents.
Eluent Degassing 219