TCD to find nitrogen and hydrogen

Discussions about GC and other "gas phase" separation techniques.

6 posts Page 1 of 1
I have a mixed sample of nitrogen and hydrogen. I need to measure both with my TCD. I am using a carrier gas of argon. I cant seem to get both peaks to show up?

I used to measure he/h using a nitrogen carrier gas and had to swap this over. I cant seem to find any literature on this.

Any help would be amazing.
You are doing all properly.

RGA analysis include permanent gas analysis on Mole sieve column with Ar carrier.

Proper mole sieves should separate N2 and H2.
Maybe you column is not conditioned properly (too much moisture trapped).

https://www.restek.com/row/chromablogra ... -analysis/
If you are looking to do low levels of both, you will not have any luck. Using argon as a carrier will not detect low levels (probably less than 1% or so - depending on the instrument) of nitrogen as the thermal conductivities of these two components are too close to each other.

In you current configuration you are probably only detecting hydrogen at any reasonable level since the difference in conductivity between argon and hydrogen is significant. If you want to detect both at low levels, you are going to have to explore some other options, helium ionization detectors coming first to mind.

Best regards
But variant %H2=100-%N2 (He carrier) is not fits for you? Or you must measure both components, or you have more 2 components?
Argon does indeed greatly reduce sensitivity for most "normal" analytes compared to He or H2 as the carrier gas since it is much closer in thermal conductivity to heavier molecules than Helium or Hydrogen.

Using Helium as the carrier gas to measure Hydrogen is not done because of strange peak shape phenomena that occur at different Hydrogen concentrations. If you are always working well above or below the inversion point where the strange phenomena occur then maybe that is not an issue for you.

Also, I found an application note by Agilent that uses 8.5% Hydrogen in their Helium carrier gas, so that both H2 and other gases including N2 can be measured w/o having to resort to Ar. Although, I did not quite follow why the small difference in conductivity between He and H2 is not an issue in addition to the inversion of thermal conductivity of mixtures of He and H2.

The application note:"Hydrogen Detection with a TCD using Mixed Carrier Gas on the Agilent Micro GC"
Arne wrote:
Also, I found an application note by Agilent that uses 8.5% Hydrogen in their Helium carrier gas, so that both H2 and other gases including N2 can be measured w/o having to resort to Ar. Although, I did not quite follow why the small difference in conductivity between He and H2 is not an issue in addition to the inversion of thermal conductivity of mixtures of He and H2.

The application note:"Hydrogen Detection with a TCD using Mixed Carrier Gas on the Agilent Micro GC"


We used 8.5% Hydrogen in their Helium carrier gas about 4 decades ago. This made hydrogen peak positive.
6 posts Page 1 of 1

Who is online

In total there is 1 user online :: 0 registered, 0 hidden and 1 guest (based on users active over the past 5 minutes)
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm

Users browsing this forum: No registered users and 1 guest

Latest Blog Posts from Separation Science

Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.

Subscribe to our eNewsletter with daily, weekly or monthly updates: Food & Beverage, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.

Liquid Chromatography

Gas Chromatography

Mass Spectrometry