Thermo Scientific Dionex UltiMate 3000 Series Operating Instructions Manual page 119

Problem
High baseline drift (Cont'd)
Strong noise, non-periodic
baseline fluctuation
Periodic baseline
fluctuation, pulsation
Peak Tailing
Peak Broadening,
increased dead time
Operating Instructions
VWD-3100 and VWD-3400RS Variable Wavelength Detectors
Probable Cause
The gradient has different
absorptions for the selected
wavelength.
The eluent is dirty or their purity
is insufficient.
The gas content of the eluent is
too high.
The detector is defective.
The lamp is too old.
The wavelength is not
appropriate, for example, solvent
absorption is too strong.
The time constant is too small.
There are pressure fluctuations
from the pump.
There are air bubbles in the
system.
Too large extra column volume
There are bad capillary
connections.
The inner diameter of the
capillary to the detector is too
large.
There are bad capillary
connections.
Too large detector cell. The
volume of the detector cell should
not exceed the smallest peak
volume by more than 1/10.
The time constant is too large.
The filter frits on the solvent lines
are clogged.
The sample loop is clogged.
UltiMate 3000 Series:
Remedial Action
Absorbing additives may
change the absorption
spectrum, depending on the
solvent. The drift that is caused
can be leveled by varying
additive concentrations.
Use fresh eluent. Use HPLC-
grade eluents only.
Degas the eluent and/or install a
restrictor at the flow cell outlet.
Contact Service.
Replace the lamp (→ pages 121
and 123).
Select an appropriate
wavelength (→ page 145).
Select an appropriate time
constant (→ page 86).
Purge the pump; check general
function (→ Pump manual).
Purge the system
(→ Pump manual).
Use short capillary connections
with a suitable inner diameter.
Use different capillaries, for
example, Viper capillaries.
Use an appropriate capillary.
Use different capillaries, for
example, Viper capillaries.
Use a smaller volume flow cell.
Select an appropriate time
constant (→ page 86).
Check the filter for
permeability. Replace the filter
frit if necessary (→ Pump
manual).
Replace the needle
(→ Autosampler manual).
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