Reduction of water with zinc for hydrogen isotope analysis

A 1-10 mg portion of water is reduced with Zn metal in a sealed tube at 450 /sup 0/C to prepare hydrogen for isotopic analysis. After reaction the tube is attached directly to the mass spectrometer without further processing. Replicate analyses of water samples give reproducibility of 0.2-0.4% (1sigma); fluid inclusion samples, 1.9%; and water of hydration of gypsum, released and reduced in the sealed tube, 1.1%. A batch of 10 samples can be prepared in 1 h.