Simultaneous determination of the H-2/H-1, O-17/O-16, and O-18/O-16 isotope abundance ratios in water by means of laser spectrometry

We demonstrate the first successful application of infrared laser spectrome try to the accurate, simultaneous determination of the relative H-2/H-1, O- 17/O-16, and O-18/O-16 isotope abundance ratios in water. The method uses a narrow Line width color center laser to record the direct absorption spect rum of low-pressure gas-phase water samples (presently 10 mu L of liquid) i n the 3-mu m spectral region. It thus avoids the laborious chemical prepara tions of the sample that are required in the case of the conventional isoto pe ratio mass spectrometer measurement. The precision of the spectroscopic technique is shown to be 0.7 parts per thousand for delta(2)H and 0.5 parts per thousand for delta(17)O and delta(18)O (delta represents the relative deviation of a sample's isotope abundance ratio with respect to that of a c alibration material), while the calibrated accuracy amounts to about 3 and 1 parts per thousand, respectively, for water with an isotopic composition in the range of the Standard Light Antarctic Precipitation and Vienna Stand ard Mean Ocean Water international standards.