A method for determining a physical property of a biological sample. The method comprises the steps of: acquiring a set of preliminary calibration signals of a first lot of a reagent using an automatic analyzer with a first photometry module; acquiring a reference set of signals of the first lot of the reagent using a calibration analyzer with a second photometry module; determining a set of module specific components by subtracting the reference set of signals from the preliminary calibration signals; acquiring a lot specific set of signals of a second lot of the reagent using the second photometry module; determining a lot calibration for the first photometry module using the set of module specific components and the lot specific set of signals; acquiring a measurement signal of the biological sample using the first photometry module and the second lot of the reagent; and determining a physical property of the biological sample using the measurement signal and the lot calibration.