Chromatography apparatus and method

A computer implemented method performed by a chromatography apparatus configured to separate molecules, having varying size, from an eluent, the method comprising:

• obtaining reference data for a chromatography column of the chromatography apparatus, wherein the reference data is indicative of elution characteristics for a set of molecular sizes,
• obtaining an elution progress measure and a corresponding quantitative measure indicative of a concentration of molecules in an eluate of the chromatography apparatus,
• estimating a size measure indicative of molecular size of the molecules in the eluate,
• rendering a representation indicative of the quantitative measure and the size measure,
• controlling a display to display the representation to a user of the chromatography apparatus,
• wherein the molecular size is estimated using a predetermined relation, comprised in the reference data, and the elution progress measure,
• further wherein the predetermined relation is indicating a curve, and the predetermined relation is obtained by performing curve fitting of value pairs comprising a gel-phase distribution coefficient (Kav) and corresponding molecular size.