Question

How does thermal conductivity detector work?

Answer 1

Thermal conductivity (TCD) is a commonly used detector in gas chromatography.  TCD works by having two parallel tubes both containing gas and heating coils. The gases are examined by comparing the heat loss rate from the heating coils into the gas. Normally one tube holds a reference gas and the sample to be tested is passed through the other.  Using this principle, a TCD senses the changes in the thermal conductivity of the column effluent and compares it to a reference flow of carrier gas. 

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