New Method for Precise Measurement of Density of Supercritical Fluid over a Wide Range of Pressure

Abstract

We have developed two methods to determine the density of supercritical fluid sealed in a tube. One is the mass-volume method that is applicable to higher densities than 0.07 g cm^-3 at 400°C when the fluid is water. In this method, the mass of the sample and the bore volume of the tube are determined precisely. The other is the chemical shift method, which takes advantage of the temperature dependence of the chemical shift and the PVT data. The latter is especially powerful at lower densities.