Thermo Scientific thermoscientific Vanquish UHPLC System Operating Manual page 122

8 • Troubleshooting
Possible Cause
UV/VIS lamp not stable
Absorption of eluent
changes when gradient
is run
Non-periodic baseline fluctuation, high noise
Possible Cause
Pressure fluctuations
from pump
Air trapped in the
system
UV/VIS lamp old or not
properly installed
Improper reference
wavelength
Detector response time
too short
Improper wavelength
or optical bandwidth
Flow cell not properly
installed
Detector defective
Optical transmission of
the flow cell too low
(Vanquish system with
VH-D10 detector only)
Periodic baseline fluctuation, pulsation
Possible Cause
Pressure fluctuations
from pump
Air trapped in the
system
Improper reference
wavelength
Page 122
Remedial Action
Allow the lamp and optics to warm up for at least 60 minutes. If the lamp is old, you
may need to replace the detector lamp (see Detector Operating Manual).
A new lamp may need burn-in time before the first analysis. For details, refer to the
Detector Operating Manual.
Absorbing additives may change the absorption spectrum, depending on the
solvent. Consider varying additive concentrations to level the drift.
Remedial Action
Purge the pump; check general function (refer to Pump Operating Manual).
Purge the system as necessary (refer to Pump Operating Manual).
Check that the lamp is correctly installed. Replace the lamp (refer to Detector
Operating Manual).
The sample must not absorb in the range of the reference wavelength. Consider
using a method without reference wavelength.
Select a suitable response time.
Select an appropriate wavelength.
Select a higher bandwidth In particular with critical conditions (low absorption, few
light).
Check that the flow cell is installed properly (refer to Detector Operating Manual).
Contact Technical Support.
Check the lamp age and replace the lamp, if necessary. Use the Cell Transmission
Check / Flow Cell Wash button on the ePanel for the module and follow the
instructions. For this procedure, a diagnostic cell for the VH‑D10 is required. If you
do not have a diagnostic cell, compare the cell transmission (light intensity) values
of the flow cell before and after a wash procedure and check whether the cell
transmission (light intensity) has increased. If it has not increased, perform an
extended wash cycle and check whether the cell transmission (light intensity) has
increased.
Remedial Action
Purge the pump; check general function (refer to Pump Operating Manual).
Purge the system (refer to Pump Operating Manual).
The sample must not absorb in the range of the reference wavelength. Consider
using a method without reference wavelength.
UHPLC System
Operating Manual