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waves in the baseline of TCD detector
Posted: Mon Jul 23, 2012 6:32 pm
by remofil
Hello, I'm using Thermo GC Ultra and in the baseline there is some sinwave. Before one mounts I replased the reduction valve of the argon background gas bottle and solve the problem but now it appear again. The valve is SIAD for laboratory usage. The pressuse in the bottle is 200 bars and 6,5 after the valve. We open the close the bottle every time we use the device. We don't touch the regulator of the valve.
Re: waves in the baseline of TCD detector
Posted: Tue Jul 24, 2012 4:00 pm
by AICMM
remofil,
This does not solve your problem (sorry) but I would advise against turning off the flow to the TCD unless it will be sitting idle for weeks at a time.
You might look at lowering the temperature of the TCD to see if this changes the characteristics of the sine wave. You might have a heater problem.
Best regards,
AICMM
Re: waves in the baseline of TCD detector
Posted: Wed Aug 01, 2012 10:27 pm
by GHGirl
Hi remofil,
I recently had the same problem. Is the vent to your TCD inside the oven?
In my case, we had the TCD vent inside the oven, and every time the oven door was closed (i.e., we had the GC running or stablizing), the baseline was just horrible - it looked like a sine wave. When we opened the GC door, the baseline stabilized. We realized the noise was coming from the TCD vent, so we just rerouted it to the outside of the oven, and our baseline problem was solved.
Hope this simple solution works for you!
GHGirl
Re: waves in the baseline of TCD detector
Posted: Fri Aug 03, 2012 7:18 am
by jdezeeuw
TCD is conductivity dependent, so it's a temperature or a flow effect you are seeing.
Temperature control can be checked by turning off the heater and see what happens with the "wave".
Flow effects: turn of carrier gas flow. Now you only have make up gas. If still there it's the make up gas regulation or the reference gas regulation.
jaap de zeeuw, Restek Corporation