Abstract: A method is provided for determining the concentration of a solution having a predetermined osmotic pressure and/or for generating a solution with a predetermined osmotic pressure. The method is performed by placing a sample of a solution into a sample cell, the sample cell including therein a membrane supported therein; sealing the sample in the sample cell; introducing gas at a predetermined elevated pressure substantially equal to the predetermined osmotic pressure; and generating a dialyzate by allowing the solution to dialyze through the membrane until equilibrium is achieved and no more dialyzate passes through while the sample cell is maintained at the predetermined elevated pressure, the sample remaining in the sample cell having an osmotic pressure substantially equal to the predetermined elevated pressure; collecting the dialyzate of said generating step; and weighing the dialyzate of said collecting step to determine the concentration of the solution remaining in the sample cell.