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341 Micro-cell Electron Capture Detector (
µ
-ECD)
Diagnostics
22 of 26
Jun 2001
Detectors
Agilent 6890 Gas Chromatograph Service Manual
Diagnostics
Frequency test
Perform this test to make sure that the base frequency for the
µ
-ECD during
a blank run indicates a relatively contaminant-free system.
Note It may take 24 hours for the
µ
-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
2 hours have elapsed since the last run.
2. Turn on the
µ
-ECD and the corresponding signal.
3. Check the displayed “Output”:
• <25 =
µ
-ECD frequency is acceptable
•
≥
1000 = Contaminants in system
Note Each display count equals a frequency of 1 Hertz (e.g., a display reading of
100 = 100 Hz.).
4. If the
µ
-ECD frequency indicates contamination (
≥
1000) check for the
following:
• Contaminated carrier gas trap(s) and or supply—replace carrier gas
supply tank and any traps on the carrier supply line.