The TCD is one of the more widely used detectors for gas chromatography because it is simple in construction, rugged, versatile, sensitive, relatively linear over a wide range, nondestructive to the sample, and inexpensive. It is because of these qualities that it continues to be widely used.

The TCD consists of a block (usually metallic) containing a cavity through which the gas flows. A heated element (resistance wire or thermistor) is positioned in the flow path of the gas. For practical considerations a differential method is usually used that requires two cavities and two heated elements. Only carrier gas passes through one cavity and the column effluent through the other. For process analysis, a reference and sample gas are used.

• Precise matching of filaments and thermistors over an extended current-resistance curve and under controlled heat dissipation conditions ensure superior detector performance
• Rigid gas and electrical leakage tests and are run on specified zero gas
• Micro-cells and GADEs are tested for signal output
• Flow-through, semi-diffusion and diffusion geometries
• Detector Sensitivity: depends on several factors. Most basic is the difference in thermal conductivity (or other characteristics) between the background (carrier, reference) gas and the sample.
• Sensitivity of hot wire thermal conductivity detectors (TCD) depends on the internal geometry, type of detector elements, and the temperature differential (Dt) between filaments and cell block.
• Thermistor detectors are at their best in sub-ambient and ambient operation.
• Gas density detectors (GADE) vary in sensitivity directly with the difference in molecular weight, as well as with the number and type of sensor elements