GE AKTA avant User Manual page 371

Problem
Distorted protein peaks
in IEX gradients (for ex-
ample step gradients).
ÄKTA avant User Manual 29035184 AE
Possible cause and action
Rapid changes of the refractive index
•
The refractive index of the buffer changes rapidly in
quick IEX gradients. The rapid change may cause light
spreading effects and disturb the shape of the protein
peaks in the U9-L 2 mm flow cell.
Run with reversed flow direction through the 2 mm
cell: connect the inlet tubing at the bottom and the
outlet tubing at the top of the flow cell.
Note:
The standard tubing (7) between the UV monitor and
the conductivity monitor is too short (170 mm) for
mounting the monitor for reversed flow direction. Per-
form the following actions:
1 Replace the standard tubing with a tubing that is
210 mm long.
2 Update the total delay volume. The increase in
volume depends on the inner diameter (i.d.) of the
tubing:
-
inner diameter (i.d.) 0.25 mm : 2 µl
-
i.d. 0.50 mm : 8 µl
-
i.d. 0.75 mm: 18 µl
-
i.d. 1.0 mm: 32 µl
8 Troubleshooting
8.3 Troubleshooting: Monitors
371