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Jun 2001
Detectors
Agilent 6890 Gas Chromatograph Service Manual
Electron Capture Detector (ECD) 340
Diagnostics
Diagnostics
Frequency test
Perform this test to make sure that the base frequency for the ECD during a
blank run indicates a relatively contaminant-free system.
Note It may take 24 hours for the ECD baseline to completely stabilize, especially
if you are starting with a cold system and want to assure high-sensitivity
operation.
Therefore, for the most accurate results, run the detector at normal operating
conditions for as long as possible (at least 2 hours and up to 24 hours) before
running the frequency test.
If you will be injecting into an unused inlet, you must use low-bleed septa.
Make sure to condition new septa before use in an inlet for several hours with
1 to 5 mL/min carrier flow.
1. Make sure you are using normal operating conditions and that at least
two hours have elapsed since the last run.
2. Turn on the ECD and the corresponding signal.
3. Check the displayed “Output”:
• <100 = ECD frequency is acceptable
• ≥100 = Contaminants in system
Note Each display count equals a frequency of 5 Hertz (e.g., a display reading of
100 = 500 Hz.).
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