Preparative free-flow isoelectric focusing: modeling and experiments.

Free-flow isoelectric focusing was adapted to preparative scale separations and chemical engineering methods were used to describe the main mechanisms operating in the apparatus. A mixture of human serum albumin (pI 4.6) and beta-lactoglobulin (pI 5.22) was separated in pH gradients, generated with carrier ampholytes of different origin and covering the pH ranges 4-6.5, 3.5-5, 4-5.5 and 4.5-5.0. Best results were obtained in the pH 4-5.5 range. The experimental results have validated the results obtained with a numerical model.