Preparative chromatography is a powerful technique for the isolation and purification of a variety of chemicals including pharmaceutical compounds, natural products and biological molecules. Scaling from an analytical HPLC column to a preparative separation can be a challenge. It is the goal of this presentation to provide practical guidelines for developing preparative HPLC separations. In the first part of this series we will cover column length, column diameter and flow rate selection. IT ALL STARTS WITH THE ANALYTICAL COLUMN!!! The use of an analytical column is the key step in developing any preparative HPLC separation. In order to develop and optimize a preparative HPLC separation a variety of analytical columns should be evaluated. The analytical column is essential in evaluating the chromatographic separation and developing a plan for scaling up to the preparative HPLC separation.