METHOD FOR MEASURING SOLUBILITY OF A SUBSTANCE IN A SOLVENT IN A SUPERCRITICAL FLUID STATE

摘要

FIELD: measurement technology.;SUBSTANCE: invention relates to analysis of composition of solution, namely to measurement of mutual solubility of substances in solid or liquid states and solvent, which is in supercritical fluid state. Method for measuring solubility of a substance in a solvent in a supercritical fluid state is carried out in a closed volume at given values of temperature and pressure and intense mixing of the substance taken in excess, to saturation state with subsequent settling to achieve equilibrium, characterized by that, at first, plotting a graph of dependence of substance solubility change in solvent, which is in supercritical fluid state, on pressure not less than at two temperatures and minimum for three values of pressure, then determining pressure values of first and second cross-over points located at intersection, two isotherms and pressure values interval between first and second crossover points of thermodynamic system, after which saturation of solvent with substance at temperature below specified temperature for pressures between first and second crossover points or at temperature above specified temperature for pressures higher than second crossover point, and after mixing before settling, preset temperature is set, reaching saturation state is determined from value of solubility constant on graph of solubility variation in time.;EFFECT: reduced value of solubility measurement uncertainty and reduced duration of substance solubility measurement in supercritical fluid solvent.;1 cl, 4 dwg, 10 tbl