HD is analyzed in water using the method described below. Although we can analyze as little as 10 uL water, this amount is hard to ship so we would recommend at least 50 uL and preferable 1 mL. Please contact us directly for shipping instructions and time needed for analysis.

The analysis of the D:H (δD) in water can now be automated using a hot chromium-reactor. This analysis works with dual inlet (DI-) or continuous flow (CF-) interfaces with the IRMS. Using these interfaces, a large number of samples can be analyzed over a 20-30 hour period.

On either DI-IRMS or CF-IRMS systems we have observed that different standards (with isotope ratios) drift at different rates over the course of the run. For example, on a Finnigan MAT H/Device™ DI-IRMS system, after adjusting for drift with a 3.5% δD standard over 23 hours, a –95% δD standard was observed to drift from –96.3 to –93.6, a 2.7% change that should have been accounted for (table #1). Using a GVI CF-IRMS system, a –391%δD standard did not change significantly over a 30 hour run but a –2% δD standard changed (drifted) to –9% δD.

Our analyses shown that this effect does not seem to be consistent; for some analyses the two standards drift together as would be expected and for others they drift apart. Since the phenomena is observed in two different instruments and using DI-IRMS and CF-IRMS sample preparation systems, it is hypothesized that variable conditions in the chromium-reactors affect the isotope ratio of different water standards in different ways, resulting in the observed behavior.

Further analyses have shown us that this effect is reproducible enough to use multiple standards and a simple spreadsheet to correct for differential drift in different standards. This drift-correction procedure results in a long term precision of better than 0.7% δD for the DI-IRMS system.