Fast high‐precision on‐line determination of hydrogen isotope ratios of water or ice by continuous‐flow isotope ratio mass spectrometry

A new fast high‐precision on‐line technique is described for the determination of hydrogen isotope ratios of water by continuous‐flow mass spectrometry. For the first time H 2 /H 2 O‐equilibration using a platinum catalyst has been used in a fully continuous process. A significant reduction in the H 2 /H 2 O‐equilibration time is achieved by a complete vaporization of the water and by increasing the exchange temperature to 100°C. The analysis time is only ∼5 min/sample which includes equilibration and processing. Measurement precision and accuracy are better than 1‰ and sample consumption is only ∼5 μL. This new technique allows the measurement of a wide range of aqueous samples either in a semi‐continuous way (discrete samples are injected one after another) or in a fully continuous way. This allows us, for the first time, to make continuous measurements of ice cores. Copyright © 2003 John Wiley & Sons, Ltd.