A Rapid, Easy, and Precise Method for Oxygen and Hydrogen Isotope Analysis of Water of Crystallization in Hydrated Minerals

Oxygen and hydrogen isotope analysis of water of crystallization is not trivial. Commonly used techniques involve off-line extraction of water from hydrated minerals and subsequent isotope analysis. Such methods are time consuming, require relatively large sample sizes and the stepwise procedure has to be carried out with extreme caution to avoid erroneous results. We present a new on-line method for analysis of oxygen and hydrogen isotope compositions of water of crystallization. Our results for gypsum (CaSO4 · 2H2O) show that the precision (1 sigma) of the method on 0.2 mg samples is better than 0.5 per mil for oxygen and 3 per mil for hydrogen isotope measurements.