Contamination (High Baseline) - Agilent Technologies 7890 Series Troubleshooting Manual

3
Chromatographic Symptoms

Contamination (high baseline)

66
3
Confirm that complete inlet maintenance has been
performed. This includes trimming and re-installing the
column.
4
Verify that the injecting device is working properly. If the
method uses a sampling valve, make a direct syringe
injection of concentration similar to that introduced by the
valve. Rule out a problem with the valve.
5
Inspect the mixing liner in the makeup gas adapter. A small
piece of graphite or sample contamination will reduce
sensitivity. See To Replace the uECD Fused Silica Indented
Mixing Liner and Install the Makeup Gas
If the ECD has a baseline higher than expected for its age, check
the following:
• Rule out all other possible causes. See
Also check carrier and detector gas supplies, supply gas
traps, and the column.
• Inspect the mixing liner in the makeup gas adapter. A small
piece of graphite can contaminate results. See
uECD Fused Silica Indented Mixing Liner and Install the
Makeup Gas Adapter.
• If the detector baseline is > 500 Hz, regardless of detector
age, bakeout the detector. Let it run for 1–2 days.
Adapter.
"Sensitivity" above.
To Replace the
Agilent 7890 Series Troubleshooting