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Free keywords:
deuterium; isotope ratio; equilibration technique; sample volume; water
deuterium
Abstract:
The hydrogen/deuterium/oxygen (H/D/O) equilibration technique for measuring isotope ratios has proved to be of great interest for a number of applications in addition to the doubly labelled water (DLW) method, which measures energy expenditure in free living subjects. However, the limiting factor of the sample volume represents a common problem in many of these methodologies. By utilizing a fully automated sample preparation device, water samples with different volumes were analysed with respect to the H-2/H-1 isotope ratios. The sample volume ranged from 4-0.25 mi. It was demonstrated that high precision was obtainable over the entire range. Although fractionation did seem to occur, it remained insignificant. Therefore, subsequent mass correction is possible and isotope ratios can be reliably obtained from water samples as small as 0.25 mi. This implies that the fully automated H/D/O equilibration technique is a valuable and useful tool for an extended range of research areas, in particular where the sample volume is limited. (C) 1998 John Wiley & Sons, Ltd.
