Operating Principle
A TCD has two microfluidic channels that are supplied with the same gas type. A switch alternates the gas flow across a heated filament between a reference gas and the carrier gas. When molecules of different thermal conductivities pass over the filament, a temperature change occurs, and the detector power is adjusted to return the filament to the original temperature. The power difference is captured as a peak. H2 and He are ideal carrier gases because they have higher thermal conductivity than most other molecules. The TCD is concentration dependent.
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