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Thermal Cleaning
If your baseline is noisy or the output value is abnormally high (> 1000 Hz), 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 and sample residues. To remove
contamination, you should perform a thermal cleaning (bakeout) of the detector. Bakeout
the detector at 20-30 degrees higher than normal operating temperature (375°C Max),
with 50-100 mL/min of makeup gas flow.
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 b and x-radiation.
Electron capture detectors must be tested for radioactive leakage at least every six
months. Records of tests and results must be maintained for possile inspection by the
Nuclear Regulatory Commission and/or the responsible local agency. More frequent tests
may be conducted when necessary.
The procedure used is a "wipe test." A wipe test kit is supplied with each new detector.
Refer to the information card supplied in the Wipe Test Kit for instructions on performing
the test.
For successful EC detection, it's important that the carrier and purge gases are very clean
and dry (99.9995% minimum purity). Moisture, oxygen, or other contaminants can result
in higher detector response but usually at the expense of both sensitivity and linear range.
Always precondition the column before connection to the detector.
A wipe test kit (P/N 18713-60050) is supplied with each new ECD. The kit includes an
information card with instructions for performing the test. Records of tests and results
must be maintained for possible inspection by the Nuclear Regulatory Commission (NRC)
and/or responsible state agency.
Radioactivity Leak Test
Gas Purity
ECD Wipe Test
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