Thermo Scientific thermoscientific Vanquish UHPLC System Operating Manual page 118

8 • Troubleshooting
Pump problems
Possible Cause
Piston seals in pump
leaking
Air trapped in pump
head
Baseline fluctuations
Pump pulsation or flow
fluctuations
Irreproducible gradient
Inappropriate detector settings
Possible Cause
Improper wavelength,
e.g., in a UV spectrum
flank
Detector response time
too short
Detector response time
too long
Injection volume variation
Possible Cause
Autosampler draws air
from vial
Air trapped in
autosampler flow path
Draw speed too high
Gas content of sample
too high or saturated
Injector needle clogged
or needle tip deformed
Piston seals in
autosampler metering
device leaking
Injection valve or other
autosampler
components leaking
Needle seat worn out
Page 118
Remedial Action
Replace the seals (refer to Pump Operating Manual).
Purge the pump (refer to Pump Operating Manual).
See "Periodic baseline fluctuations" in
See "Pressure pulsation or inconstant pressure" in
Change the gradient.
Check the solvent line filters for permeability. Replace the filter frits if necessary
(refer to Pump Operating Manual).
Remedial Action
Choose a detection wavelength that is located near the apex of the spectrum.
Select a longer response time.
Peaks are eventually not separated any more. Select a shorter response time.
Remedial Action
There is not enough amount of sample in the vial, the needle height setting is
incorrect, or there are too many replicates.
Perform a wash cycle. Check that the injection valve is in Inject position and the
flow components of the autosampler are flushed with solvent.
Select a lower draw speed.
Reduce the draw speed. Degas the sample if possible.
Replace the needle (refer to Split Sampler Operating Manual).
Replace the metering device head (refer to Split Sampler Operating Manual).
Inspect the autosampler and the connections on the injection valve. Tighten leaking
connections. Replace leaking parts (refer to Split Sampler Operating Manual).
Replace the needle seat (refer to Split Sampler Operating Manual).
Baseline (} page 121).
Pressure (} page 120).
Operating Manual
UHPLC System