Correction factor to determine total hydrogen+deuterium concentration obtained by inert gas fusion-thermal conductivity detection (IGF-TCD) technique

Abstract

The limitation of commercially available dedicated equipment based on Inert Gas Fusion-Thermal Conductivity Detection (IGF-TCD) for the determination of hydrogen+deuterium is described. For a given molar concentration, deuterium is underestimated vis a vis hydrogen because of lower thermal conductivity and not considering its molecular weight in calculations. An empirical correction factor based on the differences between the thermal conductivities of hydrogen, deuterium and the carrier gas argon, and the mole fraction of deuterium in the sample has been derived to correct the observed hydrogen+deuterium concentration. The corrected results obtained by IGF-TCD technique have been validated by determining hydrogen and deuterium contents in a few samples using an independent method based on hot vacuum extraction-quadrupole mass spectrometry (HVE-QMS). Knowledge of mole fraction of deuterium (X­_D) is necessary to effect the correction. The correction becomes insignificant at low X_D values (X_D < 0.2) as the precision in the IGF measurements is comparable with the extent of correction.