Preventive Maintenance
Electron capture detector (ECD)
Electron capture detector (ECD)
Frequency test
Note: For high sensitivity operation, and starting from a cold system, 24 hours may be necessary before baseline is completely stabilized. Use low•bleedsepta and condition a new septum prior to use in an unused inlet for several hours with 1 to 5 ml/min carrier flow rate.
Using normal operating conditions, and allowing at least two hours after the last sample was injected, enter the following:
DET
A 
( or 
B 
) 
ON 
SIG 1 
( or 
SIG 2 
) ( 
A 
or 
B 
)
If the displayed value exceeds 100 (1000 Hz), indicating a high background signal, investigate the following possibilities:
CContaminated carrier gas trap(s) and/or supply
CInsufficient column conditioning
CContaminated detector
CColumn, inlet, and/or septum bleed
CLeaks
CAnode insulation leakage
Carrier gas evaluation
Because of its very high sensitivity, the ECD is particularly prone to contamination problems, including contaminants entering the system via the carrier gas source.
The following procedure should be performed whenever a new carrier gas source is installed:
1.With the instrument on and operating normally, cool the oven to ambient, turn off the detector, turn off carrier flow to the detector, and
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