HYDROGEN ISOTOPE DETERMINATION FOR SMALL-SIZE WATER SAMPLES USING AN EQUILIBRATION TECHNIQUE

The hydrogen/deuterium/oxygen (H/D/O) equilibration technique for meas uring isotope ratios has proved to be of great interest for a number o f applications in addition to the doubly labelled water (DLW) method, which measures energy expenditure in free living subjects. However, th e limiting factor of the sample volume represents a common problem in many of these methodologies. By utilizing a fully automated sample pre paration device, water samples with different volumes were analysed wi th respect to the H-2/H-1 isotope ratios. The sample volume ranged fro m 4-0.25 mi. It was demonstrated that high precision was obtainable ov er the entire range. Although fractionation did seem to occur, it rema ined insignificant. Therefore, subsequent mass correction is possible and isotope ratios can be reliably obtained from water samples as smal l as 0.25 mi. This implies that the fully automated H/D/O equilibratio n technique is a valuable and useful tool for an extended range of res earch areas, in particular where the sample volume is limited. (C) 199 8 John Wiley & Sons, Ltd.