ACQUITY ELSD gives a noisy baseline and then a flat baseline - WKB107634

SYMPTOMS

• At a gain of 1, when flow applied, baseline is erratic, between 0 and 900 LSU
• At a gain of 100, flat baseline
• With no flow for 30 minutes to clear drift tube, normalization is 2.1

ENVIRONMENT

• ACQUITY UPLC ELS Detector

CAUSE

Extract exhaust is not working sufficiently.

FIX or WORKAROUND

Ensure that the extract exhaust is set to the correct flow.

ADDITIONAL INFORMATION

There should be a minimum negative pressure of −0.21 kPa (−0.00 bar, −0.03 psi) between the detector and the laboratory exhaust system.