GE AKTA avant User Manual page 377

Problem
Unstable pH signal
ÄKTA avant User Manual 29035184 AE
Possible cause and action
Calibration time out
•
Check the connections between pH electrode and pH
monitor.
Regenerate the pH electrode. Place the electrode in
deionized water for 30 minutes followed by 30 minutes
in a buffer with pH 4. If the pH electrode has dried out,
stronger regeneration may be needed see Section 7.5.2
Replace the pH electrode, on page 286
If persistent, replace the pH electrode. See Section 7.5.2
Replace the pH electrode, on page 286.
Bad or dried out pH electrode
•
Regenerate the pH electrode. Place the electrode in
deionized water for 30 minutes followed by 30 minutes
in a buffer with pH 4.
Clean the pH electrode. See Section 7.6.7 Clean the pH
electrode, on page 307.
If persistent, replace the pH electrode. See Section 7.5.2
Replace the pH electrode, on page 286.
Wrong mixer size for the used flow rate
•
Use the recommended mixer size for the used flow
rate. See Select Mixer chamber, on page 157.
Wrong tubing connected between the Inlet valves
•
and the System pumps
If BufferPro is run on ÄKTA avant 150 at a flow rate ≤
10 ml/min, replace the pieces of tubing marked InA
and InB with FEP tubing, o.d. 1/8", i.d. 1.6 mm. See
Tubing labels, on page 432.
pH reading unstable after column equilibration
•
A specific system wash instruction during column
equilibration is the default selection for ÄKTA avant
150 when using BufferPro. If pH readings for ÄKTA
avant 25 are unstable after column equilibration, re-
place the regular system wash instruction with the
instruction System wash BufferPro. This will increase
the run time of the method.
8 Troubleshooting
8.3 Troubleshooting: Monitors
377