A method of operating a chromatography column is described for use in methods of manufacture for producing anti-IL-12/IL-23p40 antibodies, e.g., the anti-IL-12/IL-23p40 antibody STELARA® (ustekinumab). This method involves collecting column outlet signal and accumulated flow parameters at two or more intervals of at least one mobile phase transition front during operation of the chromatography column comprising column packing. A model gamma cumulative distribution curve is calculated based on the collected column outlet signal and accumulated flow parameters for the at least one mobile phase transition front. A height equivalent theoretical plate (HETP) value is calculated for the at least one mobile phase transition front using parameters of the model gamma cumulative distribution curve and the quality of the chromatography column packing is assessed based on the calculated HETP value.