Theory and simulation of isoelectric focusing

IEF is an electrophoretic process that hinges on the mobility versus pH behavior of ampholytes. The basic theory of IEF tells us that separands focus about their pI in a Gaussian distribution. Peak height and variance depend on the competition between diffusion away from the pI and electromigration towards it. Comprehensive simulations of IEF involve the numerical solution to conservation laws for all the relevant amphoteric and ionogenic species in the separations milieu. The conservation relations are non-linearly coupled to the driving electric field and through the complicated mass-action relations. With the increased speed of microprocessors, one-dimensional simulations of the type shown here are now readily managed. The simulations offer the possibility of gaining insight into the detailed dynamics of the unfolding separations process. To see a more comprehensive exposition of IEF simulation results, particularly with regard to pH gradient development, the reader should refer the monograph by Mosher et al.