Bio-Rad BioLogic Signal Import Module (SIM) - Manual (Page 215)

TROUBLESHOOTING MAINTENANCE AND TROUBLESHOOTING
12-8
Problem Possible Cause Solution
UV trace will not If no air bubbles are present in
zero.
the flow cell, check that the cell
itself is clean both internally and
externally.
Drifting baseline. Non-homogeneous eluant perhaps
due to poor mixing or
flow rate variation.
Slow column equilibration.
If drift is due to a higher
absorbance, suspect that UV
absorbing material may be
leaching from the column.
Negative peaks. The sample is applied to the
column in a different buffer from
that used to equilibrate and elute
the column. Refractive index
changes may be responsible for
the negative peaks.
The elution buffer may have a
higher UV absorbance than the
sample components.
1. Clean the interior of the cell by passing 1M
sodium hydroxide (NaOH), water, methanol
and water through the cell. Dry the interior of
the cell with a stream of high purity nitrogen
gas (never use “house” compressed air as it
may contain oil droplets).
2. Check for leakage of liquid from the top of the
optics unit onto the outside quartz windows of
the flow cell. Clean the windows with a soft,
non-abrasive damp cloth.
3. Condensation may occur on the exterior
windows of the flow cell when moving the
optics unit from the lab to a cold room and vice
versa. Always allow an equilibration period to
compensate for such temperature effects.
1. Check flow rates of both pumps; recalibrate if
needed by selecting Gradient Pump
Calibration from the Utilities drop-down
menu.
2. Certain ion-exchangers are slow to re-
equilibrate especially if just sanitized. Allow a
longer equilibration period.
3. To confirm this, remove the column and run
deionizied (DI) water or an queous non-
absorbing buffer. If the baseline is stable, then
the column is suspect. Consult the column's
user manual for cleaning procedures.
1. Apply the sample in the same buffer used to
equilibrate the column.
2. Check the elution buffer's UV absorbance.