Thermal conductivity detector (TCD)

Thermal Conductivity Detector or GC-TCD is a technique used to analyse inorganic / permanent gases (Argon, Nitrogen, Hydrogen, Carbon Dioxide, etc) and small hydrocarbon molecules in addition to moisture . The TCD compares the thermal conductivity of two gas flows – the pure carrier (reference) gas and the sample. Changes in the temperature of the electrically-heated wires in the detector are affected by the thermal conductivity of the gas which flows around this. The changes in this thermal conductivity are sensed as a change in electrical resistance and are measured.