IMPROVEMENTS IN THE GASEOUS-HYDROGEN WATER EQUILIBRATION TECHNIQUE FOR HYDROGEN ISOTOPE RATIO ANALYSIS

Improved precision in the H-2-H2O equilibration method for delta-D analysis has been achieved in an automated system. Reduction in 1-sigma standard deviation of a single mass-spectrometer analysis to 1.3 parts-per-thousand is achieved by (1) bonding catalyst to glass rods and assigning use to specific equilibration chambers to monitor performance of catalyst, (2) improving the apparatus design, and (3) reducing the H-3+ contribution of the mass-spectrometer ion source. For replicate analysis of a water sample, the standard deviation improved to 0.8-parts-per-thousand. H2S-bearing samples and samples as small as 0.1 mL can be analyzed routinely with this method.