10.
Noisy or drifting baseline
Baseline noise or drift can be caused by a
number of system malfunctions:
flow rate
fluctuations (sometimes too small or intermittent to cause significant
retention or selectivity shifts)
air bubbles
(either in the pump or in the detector cell) due to inadquate degassing
temperature fluctuations
detector lamp
problems (especially an aging lamp)
electrical/electronic
problems (especially short-term noise)
misalignment of
the detector cell (especially in gradient separations)
UV absorbance
mismatch between solvents (in gradient separations)
contamination of
the mobile phase (sometimes hard to distinguish from extra
peaks)
an incorrectly
set detector time constant or data system sampling/bunching rate.
"garbage" peaks in a gradient run.
Ref: LC-GC, 15(10) 928 (1997)
Ref: LC-GC, 17(1) 12 (1999)
©
2006 LC Resources, Inc. all rights reserved