Abstract: The present invention is directed to a method of determining the ratio of the concentration or amounts of two or more chemical compounds and/or biopolymers, or of the relative amounts of sub-populations of closely structurally related compounds, in a multi-component mixture, extract, system, and the like using an analytical physicochemical process. The method is based on distribution of the components of the mixture (system, extract, etc.) between two or more immiscible phases and the subsequent determination of the total amounts (concentrations) of biopolymers (chemical compounds) or of the amounts (concentrations) of one or more component(s) or sub-populations of the system in the phases. The ratio between these concentrations is defined therein as the partition coefficient. The partition coefficient is used as a measure of the ratio of the amounts of two or more biopolymers (chemical compounds) or their sub-populations in a multi-component mixture (extract, system, etc.

Abstract: A method is provided for determination of the biological activity, purity and/or homogeneity of recombinant human growth hormone ("rhGH") using an analytical chemistry test. The method is based on distribution of the rhGH between two or more immiscible aqueous phases and the subsequent determination of the ratio of rhGH concentration in the phases. The ratio is then used as a relative measure of biological activity, homogeneity, and purity, when calibrated against a sample of rhGH that was previously characterized with respect to its activity, homogeneity and purity. Typical applications of this test include quality control, quality assurance, biological identity testing, etc.