The van Deemter equation has been used to derive a rule of thumb guideline for scaling. The scaling is done by the concept of time scales. The time scales are kept identical for all the columns by scaling the flow rate to the total void volume and the load to the amount of the media. The verification of theoretical background for the linear gradient elution is reported. The results demonstrate that the gradient retention behaviour of protein is independent of the column aspect ratio, but it's a function of the initial salt concentration and the gradient slop a. (c) 2006 Elsevier B.V. All rights reserved.