Scientific References

Peer Reviewed Literature: Demonstration of high-precision continuous measurements of water vapor isotopologues in laboratory and remote field deployments using wavelength-scanned cavity ring-down spectroscopy (WS-CRDS) technology


Priya Gupta, David Noone, Joseph Galewsky, Colm Sweeney, and Bruce H. Vaughn

Presented at
Rapid Communications in Mass Spectrometry 23, 16, pp. 2534-2542. August 30, 2009 Wiley


This study demonstrates the application of Wavelength-Scanned Cavity Ring-Down Spectroscopy (WS-CRDS) technology which is used to measure the stable isotopic composition of water. This isotopic water analyzer incorporates an evaporator system that allows liquid water as well as water vapor to be measured with high precision. The analyzer can measure Hmath imageO, Hmath imageO and HD16O content of the water sample simultaneously. The results of a laboratory test and two field trials with this analyzer are described. The results of these trials show that the isotopic water analyzer gives precise, accurate measurements with little or no instrument drift for the two most common isotopologues of water. In the laboratory the analyzer has a precision of 0.5 per mil for δD and 0.1 per mil for δ18O which is similar to the precision obtained by laboratory-based isotope ratio mass spectrometers. In the field, when measuring vapor samples, the analyzer has a precision of 1.0 per mil for δD and 0.2 per mil for δ18O. These results demonstrate that the isotopic water analyzer is a powerful tool that is appropriate for use in a wide range of applications and environments.