Routine Maintenance: Detectors
Maintaining a Microcell Electron Capture Detector (µECD)
Released: March 2004 6850 Series II GC User Information page 207 of 256
Thermal cleaning
If your baseline is noisy or the output value is abnormally high and you have
determined that these problems are not being caused by leaks in the GC
system, you may have contamination in the detector from column bleed. To
remove contamination, you should perform a thermal cleaning (also called
“bake-out”) of the detector.
Warning Detector disassembly and/or cleaning procedures other than thermal should be
performed only by personnel trained and licensed appropriately to handle
radioactive materials. Trace amounts of radioactive
63
Ni may be removed during
other procedures, causing possible hazardous exposure to β- and x-radiation.
Warning To prevent possible hazardous contamination of the area with radioactive
material, the detector exhaust vent always must be connected to a fume hood,
or otherwise vented in compliance with the latest revision of Title 10, CFR,
Part 20, or with state regulations with which the nuclear regulatory commis-
sion has entered into an agreement (USA only). For other countries, consult
with the appropriate agency for equivalent requirements.
Materials needed:
• Cap for the detector connection (part no. 19234-20650)
• The nut to connect the cap (part no. 19234-20570)
This procedure requires a control module or data system to edit Go set points.
1. With the detector and oven at normal operating temperatures, press
S or
T to scroll to the detector output, or view the output on the control
module or data system. Note its value for later comparison.
2. Turn off the anode purge and the makeup gas flow.
3. Cool the oven and detector to a safe handling temperature.
4. Remove the column from the detector. Make sure to cap the unconnected
end. Install the detector cap and nut into the column detector fitting to
plug the connection.
5. Make the following settings:
Detector temperature 350 to 375°C
Makeup gas flow 60 mL/min
Oven temperature
250
°C
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