Thermal conductivity detector TCD is also known as hot wire detector. Here, measurements are made according to the thermal conductivity Inside technique is a Wheatstone bridge The principle here is, as the gas is passed over a heated element, the temperature and therefore the resistance of the filament wire will vary according to the thermal conductivity of the gas. So as long as there is no sample gas in the effluent, the resistance of the wire of the Wheatstone bridge will be the same. But when the sample components are eluted with the carrier gas, a small change in the system occurs in the effluent arm. And these filament arms in the opposite arm of the Wheatstone bridge. Quantitative parameter is the change in resistance (R). Change in resistance α concentration of the sample components Almost all gases will give a response to this, since known as universal detector for GLC. Advantages:- 1. Simple 2. Reproducible Disadvantages :- 1. Not very sensitive
Posted on: Mon, 05 Aug 2013 13:00:01 +0000
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