Analysis of Hydrogen and Oxygen Isotope in Water Sample Using Isotope Ratio Mass Spectrometry and Laser Spectroscopy

The stable isotopes of hydrogen and oxygen (δ²H and δ¹⁸O) are excellent tracers for studying on the natural water cycle. New analytical techniques for stable isotope ratio measurements have been rapidly developed over the past decade. These techniques include mass spectrometry with online or continuous flow apparatus for sample introduction, and laser spectroscopy. In this paper, the δ¹⁸O value of water samples was determined by CO₂-H₂O equilibration-isotope ratio mass spectrometry and laser spectroscopy, and the δ²H value was determined by the laser spectroscopy and high-temperature conversion/elemental analysis-isotope ratio mass spectrometry (HTC-IRMS). The results show that the measurement accuracy and precision of two methods are almost same when determining the δ²H and δ¹⁸O value of the groundwater, seawater and meteoric water samples. While, laser spectroscopy has the advantage of fast and efficient, low cost and few sample consumption. The two methods were also used to determine the extraction water from soil samples. The δ¹⁸O value deviation between the measurement and true value of laser spectroscopy technology is 0.34‰, and that of mass spectrometry is less than 0.10‰. Theδ²H value deviation between the measurement and true value of laser spectroscopy technology is 2.3‰, and that of mass spectrometry is less than 0.6‰. The results indicate that mass spectrometry is much better than laser spectroscopy technology for the determination of water samples containing organic matter.