Advances in process chromatography gradient elution using binary linear gradients

A number of chromatography techniques utilize mobile phase gradients with c hanging buffer concentration to effect separation. At process scale the maj ority of gradients are stepwise or isocratic. There are a number of instanc es where process performance or economics indicate that linear gradients wo uld deliver better theoretical performance. However, to date this process a dvantage has not been implemented due to concerns about the accuracy, relia bility or reproducibility of equipment used to produce linear changes in gr adient composition. In this manuscript, recent developments in simple feedf orward control and data from the resultant process-scale performance are pr esented. Information is provided on the practical heuristics underlying the control strategy. The data presented in this paper illustrate how the feed forward control strategy has been implemented on a commercial system to ach ieve better than +/-2% accuracy of process-scale linear gradients. (C) 2001 Published by Elsevier Science B.V.