Accuracy and precision of flowing afterglow mass spectrometry for the determination of the deuterium abundance in the headspace of aqueous liquids and exhaled breath water.

We have assessed the accuracy and precision of our flowing afterglow mass spectrometric method (FA-MS) for absolute measurements of deuterium abundance in water using standardised tap water/D(2)O mixtures within the D/H range from 155 ppm (local tap water) to 1104 ppm, prepared by the gravimetric method. The results of this study show that a precision and accuracy of 1% can be achieved for the deuterium abundance in water samples. This is quite adequate for the main application, which is the rapid, non-invasive measurement of total body water by deuterium analysis of breath water vapour using the D(2)O dilution method.