Bio-Rad ChromLab™ Software - Manual (Page 258)

B | Troubleshooting the Instrument
256 | NGC Chromatography Systems and ChromLab Software
The baseline is drifting. The eluant is nonhomogeneous
perhaps due to poor mixing or
flow rate variation.  Check the flow rates of both
system pumps.
 Recalibrate both system
pumps. In ChromLab, select
Tools > Calibrate > Pump
Flow Rate. Complete the
calibration steps in the dialog
box.
The column equilibration is slow. Certain ion exchangers are slow
to re-equilibrate, especially when
just sanitized. Allow a longer
equilibration period.
If drift is due to a higher
absorbance, UV absorbing
material might be leaching from
the column. To confirm this, remove the
column and run deionized water
or an aqueous nonabsorbing
buffer. If the baseline is stable,
then the column is suspect.
Tip: Consult the column’s
user manual for cleaning
procedures.
Negative peaks are
present. The sample is applied to the
column in a buffer that is different
from that used to equilibrate and
elute the column. Refractive index
changes might be responsible for
the negative peaks. Apply the sample in the same
buffer used to equilibrate the
column.
The elution buffer might have a
higher UV absorbance than the
sample components. Verify the UV absorbance of the
elution buffer.
Symptom Possible Cause Possible Solution