Noisy baseline on UPC2 PDA after CO2 tank change - WKB75070

SYMPTOMS

• Noisy baseline after changing CO₂ tank
• ABPR Health test passes
• Leak test passes
• CO₂ cooling heads are holding at the correct temperatures
• Changing co-solvent has no effect
• CO₂ is 99.995% pure with diptube
• Noise is minimized at wavelengths above 254 nm
• 

ENVIRONMENT

• ACQUITY UPC2 PDA Detector

CAUSE

Low-level CO₂ contaminants are entering the system through the liquid CO₂.

FIX or WORKAROUND

Use food grade or better gaseous CO₂ (no diptube).

ADDITIONAL INFORMATION

UPC2 does not require liquid CO_² from a tank. The ccBSM can compress gaseous CO₂ into a liquid. Low-level contaminants are left in the tank as CO₂ boils off.