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FLAME IONIZATION/DRY ELECTROLYTIC CONDUCTIVITY DETECTOR (FID/DELCD) The FID/DELCD detector is one of the most useful GC detectors because it allows the operator to reliably identify FID peaks as halogenated or not. The DELCD actually measures the ClO2 present in the FID exhaust gas. Because the FID combusts the sample upstream of the DELCD, all hydrocarbons are converted to CO2 and H20 prior to the DELCD, completely preventing large hydrocarbon peaks from contaminating the DELCD. The DELCD operates at close to 1000°C and can tolerate the water-saturated FID effluent and measure the chlorine or bromine content simultaneously with the FID measurement of the hydrocarbon content. This is especially beneficial for measuring chlorinated VOCs under a solvent peak as shown in the example chromatogram above, pesticides or in measuring PCB peaks obscured under large amounts of diesel fuel. While approximately 100
times less sensitive than an ECD detector, the DELCD is
much more selective than the ECD which can eliminate
interferences which would complicate an ECD analysis.
Sample preparation which might be required for ECD work
is not required for the DELCD because of its total
selectivity and because the FID pre-combusts any
contaminants. The FID/DELCD is supplied with dual
amplifiers for two simultaneous chromatograms and comes
with a spare DELCD detector assembly.
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