Absolute isotopic scale for deuterium analysis of natural waters. Absolute D/H ratio for SMOW1

The absolute isotopic ratios of the hydrogen content of two reference water standards called “SMOW”² and “SLAP³ were measured to define an absolute isotopic scale. This isotopic scale can be used to normalize measurements of the natural isotopic variations in waters. The principle of the method used to define the zero of the scale is given. The absolute D/H ratios of SMOW and SLAP were measured by mass spectrometric comparison with calibration mixtures prepared in the laboratory. The following values are obtained:

(D/H)_SMOW = 155.76±0.05 × 10^–6

(D/H)_SLAP = 89.02±0.05 × 10^–6

δ⁰/00 SLAP/SMOV= 428.50±0.10

Samples of about 20 cc of the reference standards SMOW and SLAP are available from the International Atomic Energy Agency, on request.