Waters Prep Series Installation And Maintenance Manual page 189

The degassing operation should be as efficient as possible. To remove the gas
as quickly as possible, be aware of the following considerations:
• Helium sparging gives stable baselines and better sensitivity in a
fluorescence detector, and prevents the reabsorption of atmospheric
gases. Solvents sparged with helium generally are well degassed by the
time they reach the pump because the helium will diffuse out of the
solvent into the atmosphere through the PTFE tubing connecting the
reservoirs to the pump. The solvent arrives at the pump with less than 1
atmosphere partial pressure of helium.
• Vacuum alone is too slow as an acceptable means of degassing solvent.
Warning:
bottles in which solvent is shipped. They stand a high risk of
implosion under these conditions.
In the techniques listed above, except for helium sparging, the solvent
reequilibrates to air saturation in 12 to 24 hours (depending on the solvent).
Degassing by vacuum or sonification is often performed for improved pump
performance in high-pressure applications but might not yield the required
baseline stability for high-sensitivity absorbance detection. Therefore, the
most practical solution for most applications is helium sparging since, due to
the low solubility of the gases used, it does not impair pump performance in
most solvents.
It is dangerous to apply vacuum to the brown gallon
Solvent degassing methods D-9