Waters Alliance e2695 Operator's Manual page 174

Table 8–9: Chromatography troubleshooting (continued)
Symptom
Carryover is seen from
previous injection
Flat baseline,
no peaks
Flat-topped peaks
Possible cause
Previous injection is
exceedingly high in
concentration
Choice of needle wash solvent
is insufficient to solubilize all
sample components.
Lower needle wash frit (if so
equipped) is contaminated
No solvent flow
Lamp not ignited
Detector not zeroed
Improper connection between
detector and recorder or data
system
Incorrect wavelength
Leak in solvent path
Detector not zeroed
Incorrect input voltage setting:
• Recorder
• Analog-to-digital converter
Sensitivity too high
Sample concentration or
injection volume exceeds
voltage output of detector
February 27, 2018, 715003794 Rev. C
Page 174
Corrective action
Calculate mass injected. Try
re-injecting a larger volume of
less concentrated solution
while keeping injected mass
constant.
Choose a needle wash solvent
that solubilizes all
components.
Replace lower needle wash frit
Determine flow rate.
Use detector diagnostics to
determine reference/sample
energy. Zero energy indicates
lamp not ignited.
Ignite lamp. If this does not
resolve the problem, replace
the lamp.
Zero the detector baseline.
Examine cabling between the
detector and the recorder.
Ensure correct wavelength
setting.
Inspect fittings.
Zero the detector baseline.
Adjust input voltage setting or
detector output cable to
correct position.
Select a less sensitive
detection range.
Decrease sample
concentration or injection
volume.