Possible cause and actionProblem
•
Bad pump function
Check that the pump is operating properly. See Select Mixer
chamber, on page 152 for example of pump pressure curves.
•
Poor mixing function
Check the mixer chamber size and change the chamber if neces-
sary. See Select Mixer chamber, on page 152.
Check the function of the mixer. Place a stirrer bar in the palm
of your hand. Hold the hand above the mixer. The stirrer should
move when the mixer is activated.
Check that the mixer chamber is free from solids. To open the
mixer, see Section 7.3.2 Replace the inline filter, on page 266.
Unstable signal
•
Large difference in refractive index between buffer A and buffer
B
Due to light spreading effects in the UV cell, the buffer with the
highest UV absorption shows the lowest UV absorption in the
chromatogram, and the buffer with the lowest UV absorption
shows the highest UV absorption. This can occur if there is a large
difference in refractive index between buffer A and buffer B and
the UV is run at high sensitivity.
The UV curve shows a gradi-
ent that is inverted com-
pared to the expected gradi-
ent
UV monitor U9-L
Possible cause and actionProblem
•
Wrong UV flow cell for current buffer
Change to a shorter UV flow cell or change buffer.
•
The UV flow cell is not correctly installed
Check that the UV flow cell is fitted correctly, see Section 7.8.6
Replace the UV monitor U9-L flow cell, on page 328.
•
Broken UV flow cell
Replace the cell, see Section 7.8.6 Replace the UV monitor U9-L
flow cell, on page 328.
Autozero out of accepted
range
364 ÄKTA pure User Manual 29119969 AB
8 Troubleshooting
8.3 Troubleshooting: Monitors
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