Poor area and height peak precision with ACQUITY ELSD - WKB101690

SYMPTOMS

• %RSDs of area and height fail SQT System Precision (>5.0%)
• Reproducibility on same injections with TUV show very good precision
• Exhaust tubing goes up and over ELSD exhaust vent pipe on other side of lab
• Some days ELSD precision injections pass (~3-4%), other days they fail at >10% %RSD

ENVIRONMENT

• ACQUITY UPLC ELS Detector
• 2424 Evaporative Light Scattering Detector

CAUSE

ELSD exhaust tubing is routed above ceiling tiles, where temperature and humidity vary day to day.

Condensation in the long exhaust line cannot reach the trap bottle.

FIX or WORKAROUND

Reroute exhaust tubing to stay within the room (under ceiling tiles) and keep it at room temperature.

ADDITIONAL INFORMATION