[Bidagdha_TADIR]

I was studying GC and I understantd that use of Thermal conductivity detector requires using a reference cell where only pure carrier gas will enter. I also learned that this is particularly important where the temperature is programmed. The books are calling it reference gas flow.

My question is, is there another chromatographic column in the instrument to give this reference flow? If so, then doesn't this make TCD highly disadvantageous?

[marquis]

The classical method requires two identical columns to feed the thermal conductivity detector (TCD).
However, many instrument companies bypass this by switching between the carrier gas and the
column output.  Agilent is one company who set up the system for us.

When the  TCD is running,the detector sounds like a weak buzzer.

Hope this helps. 

[Bidagdha_TADIR]

Thank you, this makes clear.

But about switching column output, doesn't that mean that carrier gas won't be at same temperature as the column output (since the carrier gas is not entering the column)? Then TCD becomes useless, doesn't it?

[marquis]

You need to talk to the instrument manufacturers for the details.

It didn't cause problems for us.  Most of our work was isothermal
(fixed temperature). But not all of it was.  Didn't have any problems.

Good luck.