universal calibration

in chromatography
A calibration of a size-exclusion chromatography set-up based on the finding that the retention volume of a molecular or particulate species is a single-valued function of an appropriate size parameter of this molecule or particle, irrespective of its chemical nature and structure. The product of the intrinsic viscosity and molar mass, [ η ] M, has been widely used as the size parameter.
Purple Book, p. 69