2998 PDA detector with Arc fails SQT noise test but passes drift test - WKB247756

SYMPTOMS

• Noise spikes cause failure of SQT noise test during the noise and drift 
• All other SQT tests successful
• Drift test successful

ENVIRONMENT

• 2998 PDA Detector with Arc

CAUSE

If the outlet tubing from the flow cell of the PDA detector is cut incorrectly, or if it has some type of internal anomaly, you get an effect known as "water hammer" or transient back pressure. This water hammering creates pulses in the outlet stream that then reach the flow cell and show up in the detector as noise. The high level of noise causes the test to fail.   

This issue is specific to PDA detectors with Arc HPLC, because they do not require a back pressure regulator.

FIX or WORKAROUND

Replace the outlet tubing from the flow cell and cut it properly using a tube cutting tool. The part number for the tubing with the back-pressure regulator is 700010006.

ADDITIONAL INFORMATION