Thermo Scientific thermoscientific Vanquish UHPLC System, Operating Manual

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8 • Troubleshooting
Page 116 UHPLC System
Operating Manual
Possible Cause Remedial Action
Capillaries clogged Replace the capillaries.
Sample loop clogged Replace the sample loop (refer to Split Sampler Operating Manual ).
Solvent selector/
proportioning valve
defective Contact Technical Support.
8.2.2 Ghost Peaks, Negative Peaks and Spikes
Ghost peaks
Possible Cause Remedial Action
Contamination
(typically injector or
column) Flush the system using an appropriate solvent.
Improper reference
wavelength The sample must not absorb in the range of the reference wavelength. Consider
using a method without reference wavelength.
Selected bandwidth too
high Select a lower bandwidth.
Degassing channels
contaminated Purge the pump (all channels) to rinse the degassing channels (refer to Pump
Operating Manual ).
Negative peaks
Possible Cause Remedial Action
Improper reference
wavelength The sample must not absorb in the range of the reference wavelength. Consider
using a method without reference wavelength.
Wrong polarization of
analog output If you are using analog output, check the analog output polarization.
Spikes
Possible Cause Remedial Action
Air trapped in flow cell • 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!
Particles in flow cell • Flush the system (see Flushing the System ( } page 81) ). If you suspect that a
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.
UV/VIS lamp old,
defective, or not
properly installed Check if the lamp is properly seated. Replace the lamp (refer to Detector Operating
Manual ).