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Jun 2001
Detectors
Agilent 6890 Gas Chromatograph Service Manual
Micro-cell Electron Capture Detector (µ-ECD) 341
Diagnostics
• Insufficient column conditioning—fully condition the column.
• Contaminated detector—bake out the detector.
• Column, inlet and/or septum bleed—clean the inlet/replace the
septum with a conditioned, low bleed septum.
• Leaks—perform leak tests on both the inlet and detector systems.
• Anode current leakage—make sure the anode contacts are clean.
Make sure the anode nut is tight.
Leak test
Note Once you have determined that the flow system components upstream from
the detector (gas supply tubing, inlet, column fittings) are leak free, perform
the following µ-ECD detector leak test.
1. With the GC on and operating normally, set the oven, detector, and inlet
temperatures to ambient.
2. Turn off the µ-ECD and then turn off the inlet pressure.
3. Turn off the anode and makeup gas flows.
4. Cap the µ-ECD exhaust vent with a vent plug (part no. 5060-9055).
5. Set carrier gas pressure at the inlet corresponding to the µ-ECD to 15 psi
(103 kPa).
6. Wait until the system reaches the setpoint pressure and then turn off the
pressure and monitor the actual pressure value for at least 10 minutes.
7. Check for pressure drop:
• If the pressure stays stable or drops only 0.5 psi, you can consider
the µ-ECD leak-free.
• If the pressure drops more than 0.5 psi, you have a leak.
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