Osmometric device and process for determining the analyte content of a solution of mixed substances

A method of determining the content of an analyte in an unassayed solution of a mixture of said analyte with at least one more substance in a fluid flow subject to chemical analysis using an osmometric measuring device including inner and outer osmotic cells separated by an inner rigid or rigidly supported membrane permitting the establishment of different pressures in said inner and outer osmotic cells and being impermeable for said analyte but permeable for an osmoticum in said cells, a pressure measuring device arranged in pressure transmitting communication with said inner cell for determining the pressure of said osmoticum therein and a fluid conduit structure disposed adjacent said outer osmotic cell and being separated therefrom by an outer osmotic membrane which is permeable for said analyte but impermeable for other substances in said unassayed solution, said osmotic cells including initially both the same osmoticum with the same osmolarity in an initial or regenerated basic state, said method comprising the steps of:

• admitting to said fluid conduit structure, which extends along said outer membrane, first a solvent-type solution (containing substantially a chemical solvent) for establishing a certain operating pressure, then admitting to said fluid conduit structure said unassayed solution of said mixture of substances including said analyte to cause a resulting pressure over time distribution in said inner osmotic cell and determining from the hydrostatic pressure change measured in said inner osmotic cell as a result of the permeation of said analyte into said outer osmotic cell, the content of said analyte in said unassayed solution of said mixture of substances.