Isotope effects in water. Tracer diffusion coefficients for H218O in ordinary water

A method is described for measuring the tracer diffusion coefficient of H218O in ordinary water. The method combines the conventional diaphragm cell technique with isotope ratio mass-spectrometric determination of tracer concentrations and gives diffusion coefficients of very high precision. The accuracy of the method is limited only by the accuracy of calibration of diaphragm cells and is such that the isotope effect for water diffusion has been measured precisely. Results are presented for temperatures from 278 to 323 K at 0.1 MPa, and for pressures up to 262.5 MPa at 323 K