GE AKTA avant User Manual page 367

Problem
Baseline drift or noisy
signal
ÄKTA avant User Manual 29035184 AE
Possible cause and action
Flow restrictor in off-line position
•
Use the Flow restrictor. Use the pH valve instruction
to manually set the Flow restrictor inline (Flow path:pH
valve:Restrictor in-line), or select the Flow restrictor
in the Method Settings phase of a method.
Air in the UV flow cell
•
Use the Flow restrictor.
Remove the air by flushing the cell with water or
buffer.
If persistent, clean the UV cell. See Section 7.5.1 Clean
the UV flow cell, on page 283.
Air in buffers
•
De-gas if necessary.
Make sure that both the instrument and the buffers
•
have reached the ambient temperature.
Impure buffers
•
Check if the signal is noisy with water.
Unclean optical fiber connectors
•
Clean the connectors. See Section 7.8.4 Replace the
UV monitor U9-M flow cell, on page 342.
Dirt in the UV flow cell
•
Perform a System CIP. See Section 7.6.2 Perform Sys-
tem CIP, on page 289.
If necessary, manually clean the UV cell. See Sec-
tion 7.5.1 Clean the UV flow cell, on page 283.
Wrong type of UV cell is used
•
If a UV cell with 2 mm path length is to be used, use
only cells marked U9-2.
8 Troubleshooting
8.3 Troubleshooting: Monitors
367