Technically it probably works, but sensitivity decreases since thermal conductivity in TC detector is dependent on the difference between gas masses: difference between helium (4 g/mol) and SO2 (64 g/mol) masses is much bigger than between N2 (28 g/mol) and SO2, but might be still enough, if there is lots of S in samples.

Furthermore, as an example TCD in GC:s can be used to measure hydrogen (2 g/mol) by using N2 as carrier gas, then helium is not ok because too small mass difference.


Hannu Nykänen


University Researcher

University of Eastern Finland, Kuopio



“New” article about peat carbon stable isotopes:





From: Stable Isotope Geochemistry <[log in to unmask]> On Behalf Of Jason Curtis
Sent: keskiviikko 3. heinäkuuta 2019 22.00
To: [log in to unmask]
Subject: [ISOGEOCHEM] Helium saving question - EA for percent S


Has anyone ever tried using nitrogen as the carrier gas in an elemental analyzer when measuring percent S?  Not isotopes or %C and %N.  I don’t see an issue except the baseline would be very high.  I also don’t see how the thermoconductivity detector (TCD) would mind.


If no one warns me against it, I will try it on a Carlo Erba NA1500.  I’ll use UHP N2 for the carrier, reference, and the autosampler purge gases.  And just adjust the baseline down.  If it works (or does not work) I will report back.


Thanks in advance for any advice,


Jason Curtis, Ph.D.
Stable Isotope Mass Spec Lab manager
Senior Associate-In Geochemistry
Department of Geological Sciences
University of Florida
Gainesville, FL 32611