Thermo Scientific TRACE GC Ultra Maintenance And Troubleshooting Manual page 393

Baseline
Behavior Characteristics
High-standing current
Dip after solvent
peak
Irregular S-shaped
shape
Square waves
High-frequency
Noise
noise
Maintenance and Troubleshooting Manual
Cause
Excessive column
stationary phase bleeding
Loose connections
Detector contaminated
Excessive column bleed
during column temperature
programming
Oxygen contamination is
decomposing the stationary
phase
Large AC power
fluctuations; heavy
equipment on same line
Contaminated detector
Combustion-gas flow too
low or too high
Contaminated column
Contaminated detector gas
supply
Defective electrometer
Analytical Troubleshooting
Remedy
Check the oven temperature,
ensuring it doesn't exceed the
column upper limit.
Recondition the column.
Replace the column.
Ensure all interconnections and
screw connections are tight.
Bake out or clean the detector.
Reduce the upper column
temperature. Bake out the
column. Install a high
temperature column.
Install oxygen filters in carrier
gas line.Check pneumatic and
inlet systems for leaks. Use
correct gas purity with low
oxygen content.
Use a dedicated clean AC line of
sufficient amperage
Isolate the detector from
electronics. If noise disappears,
clean the collector.
Check the detector-gas flows
Condition the column.
Check the gas purity and install
appropriate filters
Replace electrometer.
Chapter 19
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