Action
Comment
Problem
•
Use appropriate test molecule and con-
ditions, e.g. use salt for SOURCE media.
Test molecule interacts with
the chromatography
medium under the
conditions used, e.g. acetone
interacts with SOURCE me-
dia.
HETP values
unrealistically low
(number of theoretical
plates too high).
•
Adjust the chromatogram in UNICORN
to correct the retention volume. See
UNICORN manual for further informa-
tion.
The volume measurement
failed to reset at start of
sample elution, resulting in a
very high retention volume.
•
Inspect the bed support for damage and
replace if necessary.
Leaking adapter bed
support.
Unstable base line.
•
Inspect the bed support for damage and
replace if necessary.
Leaking bottom bed support.
•
Liquid velocity should be in the range
15-60 cm/h depending on particle size.
The smaller the particle, the higher the
velocity.
Liquid velocity too high or
too low.
High HETP value.
•
Use a sample volume that is maximum
2% of the column volume.
Too large sample volume
(gives a broad peak).
•
Shorten these distances (minimizes dilu-
tion).
Too great a distance
between the sample injection
and column inlet, or between
the column outlet and
analyzing instrument.
•
Minimize dilution by reducing the liquid
volume. For example, if the inner diame-
ters of the tubing, valves, connectors,
etc. are wider than the column inlet and
outlet, change them to the same diame-
ter.
Large liquid volume in tubing,
valves, connectors, etc.
AxiChrom 50, 70 and 100 columns Operating instructions 28-9331-08 AG
147
7 Troubleshooting
7.1 Performance
