GE AKTAprime plus Operating Instructions Manual page 55

Error symptom
Incorrect or unstable
pH reading
ÄKTAprime plus Operating Instructions 28-9597-89 AB
Possible cause
Problem with elec-
trode
Incorrect pump or
valve operation
Air in the flow cell
Static interference
6 Troubleshooting
6.3 pH curve problems
Corrective action
Check that the electrode cable is
connected properly.
Check that the electrode is correct-
ly inserted in the flow cell and, if
necessary, hand-tighten the nut.
Check that the pH electrode is not
broken.
Calibrate the pH electrode.
Clean the pH electrode if required,
see Monitor pH/C-900 User Manual.
Compare the response of the pH
electrode with that of another pH
electrode. If the response differ
greatly, the electrode may require
cleaning or replacement.
In organic solvents such as
ethanol, methanol and acetonitrile,
stable pH measurements are not
possible since dehydration of the
membrane will occur. It is recom-
mended that the pH electrode is
not used in applications using or-
ganic solvents. Mount the dummy
electrode instead.
Check that the pump and valves
operate correctly.
If air in the flow cell is suspected,
tap the flow cell carefully or tilt it
to remove the air. Alternatively,
flush the cell with buffer at 20
ml/min (E 100 system) or 10 ml/min
(E 10 system) for 1/2 min. Use the
flow restrictor FR-902 after the pH
electrode.
There may be interference from
static fields. Connect the pH flow
cell and the rear panel of the
monitor using a standard laborato-
ry 4 mm "banana plug" cable.
55