On the base of developed model for electrokinetic sample motion was conducted numerical experiment for separation of albumin bounded bilirubin along sample zone in buffer solution through straight separation channel made of polymethylmethacrylate within microfluidic chip under different pH of buffer solution, voltage applied to channels ends, channel length. On the basis of the simulations by finite-difference method the effects of the channel size, the chip material, the applied voltage difference and pH on separation rate are discussed.