Abstract: In a process for the determination of the concentration of a substance dissolved in a solvent by means of an osmometer, comprising a two-chamber system with a first chamber having an osmosis cell and a second chamber for the measurement solution, to shorten the measurement time and to improve the separation of permeating components during the measurement of the concentration of the substances in the measurement solution, the pressure in the osmosis cell is held constant with an incompressible membrane arrangement, whereby with a pressure measurement apparatus in the second chamber after the replacement of a solvent, a reference solution or a calibration solution by a measurement solution, a pressure curve which corresponds to the concentrations of the nonpermeating substance and permeating substances or to the flows of the permeating substances between the osmosis cell and the second chamber is measured, and by analysis of the curve, the concentration of the nonpermeating and permeating substances in the meas

Abstract: The invention relates to methods for the determination of the concentration of substances dissolved in a solution by means of an osmotic cell, using a pressure measurement device, and an apparatus incorporating the aforesaid osmotic cell with pressure measurement device. According to a first method, the concentrations of the substances are determined by the formation of the differences between a final pressure which is established after contact with the solution and an original and minimum pressure. According to a second method, the pressure/time course of biphasic response curves is analyzed in the vicinity of the minimum pressure, along with the rate constant for the exponential pressure increase which takes place after the minimum pressure, and the concentrations of the substances are then computed.