Ghost Peaks, Negative Peaks And Spikes - Thermo Scientific thermoscientific Vanquish UHPLC System Operating Manual

8 • Troubleshooting
Possible Cause
Capillaries clogged
Sample loop clogged
Solvent selector/
proportioning valve
defective
8.2.2

Ghost Peaks, Negative Peaks and Spikes

Ghost peaks
Possible Cause
Contamination
(typically injector or
column)
Improper reference
wavelength
Selected bandwidth too
high
Degassing channels
contaminated
Negative peaks
Possible Cause
Improper reference
wavelength
Wrong polarization of
analog output
Spikes
Possible Cause
Air trapped in flow cell
Particles in flow cell
UV/VIS lamp old,
defective, or not
properly installed
Page 116
Remedial Action
Replace the capillaries.
Replace the sample loop (refer to Split Sampler Operating Manual).
Contact Technical Support.
Remedial Action
Flush the system using an appropriate solvent.
The sample must not absorb in the range of the reference wavelength. Consider
using a method without reference wavelength.
Select a lower bandwidth.
Purge the pump (all channels) to rinse the degassing channels (refer to Pump
Operating Manual).
Remedial Action
The sample must not absorb in the range of the reference wavelength. Consider
using a method without reference wavelength.
If you are using analog output, check the analog output polarization.
Remedial Action
• Check all fluid connections for tightness, in particular in the intake path.
• Degas the mobile phase.
• Install a restrictor at the flow cell outlet, observing the pressure specification of
the respective flow cell and the general guidelines for the flow cell.
Note: Excessive backpressure will destroy flow cells!
• Flush the system (see Flushing the System
capillary is contaminated with particles, in particular between the column and the
flow cell, replace the capillary.
• Flush the flow cell with different flows if particles are trapped in flow cell.
• Check if the column is defective.
Check if the lamp is properly seated. Replace the lamp (refer to Detector Operating
Manual).
(} page 81)). If you suspect that a
UHPLC System
Operating Manual