Capillary zone electrophoresis method for the direct determination of amino acids in recombinant human erythropoietin preparations used for the treatment of anemia.

A method based on CZE for the determination of glutamic acid, glycine, and alanine in a biopharmaceutical formulation containing recombinant human erythropoietin was developed. The separation was achieved within less than 5 min, using a fused-silica capillary column (55 cm × 50 μm id) and 30 mmol/L phosphate buffer at pH 11.5, containing 0.