Cyclic baseline on ACQUITY UPLC H-Class PDA system - WKB73348

SYMPTOMS

• Cyclic baseline when running samples on ACQUITY H-Class PDA system. 
• Cleaning the instrument does not resolve the issue.
• Monitoring baseline with no flow does not indicate an electronic issue.
• PDA energy looks good. 
• When monitoring baseline, accumulator pump trace looks like there is an issue with the check valve.

ENVIRONMENT

• ACQUITY UPLC H-Class
• ACQUITY UPLC PDA Detector
• ACQUITY UPLC H-Class Quaternary Solvent Manager (QSM)

CAUSE

QSM accumulator check valve is sticking.

FIX or WORKAROUND

Replace the accumulator check valve.

ADDITIONAL INFORMATION

QSM accumulator check valve: 700005164 (CHECK VALVE, DOUBLE BALL AND SEAT, 1PK)