热导检测器

Thermal conductivity detector (TCD), also known as thermal conductivity of the pool or hot wire, is the most commonly used gas chromatography a detector. A thermal conductivity detector operating on the principle that the different components have different thermal conductivities from the carrier gas. Sensitive components for the hot wire, such as tungsten wire, platinum wire, rhenium wire, and the composition of the bridge by the hot wire. After a constant current, the temperature of the tungsten filament is increased, and the heat is transferred to the cell wall by the carrier gas around it. When the measured component and the carrier gas into the thermal conductivity pool, the mixed gas thermal conductivity and pure carrier gas is different (usually lower than the thermal conductivity of the carrier gas), tungsten wire to the wall of the heat also occurred Change, resulting in tungsten wire temperature changes, the resistance also will change, and then make the bridge output unbalanced potential and as a signal output. Thermal conductivity detector is the first appearance of gas chromatography and the most widely used detector.

 

In recent years, although in many ways it has been more sensitive and more specific detector replaced, but because it has a simple structure, stable performance, sensitivity, suitable for a wide linear range for a variety of substances can have chromatography Response, the most suitable for microanalysis (ppm level). In the analytical test, the thermal conductivity detector is not only used for the analysis of organic pollutants, but also for the analysis of some other detectors can not detect inorganic gases such as hydrogen, oxygen, nitrogen, carbon monoxide, carbon dioxide and so on.