RECOMBINANT HUMAN INSULIN .6. DETERMINATION OF RECOMBINANT HUMAN PROINSULIN BY CAPILLARY ZONE ELECTROPHORESIS - OPTIMIZATION OF EFFICIENCY AND SELECTIVITY

The optimization of the separation of recombinant human insulin (rhI) and recombinant human proinsulin (rhP) by free-solution capillary zone electrophoresis in uncoated fused-silica capillaries with ionic and zwitterionic buffers was carried out. The relationship between the selectivity and pH of the buffer was established. The effects of pH and ionic strength of the buffer on protein adsorption on the capillary walls and Taylor diffusion was investigated. The separation of rhI and rhP with an efficiency of 200000 theoretical plates was achieved using 20 mM Na2HPO4-NaOH buffer (pH 11.2). The proposed method allows the simultaneously determination of rhP and some rhI degradation products (which are also included in pharmacopoeias) in pharmacopoeially limited amounts in rhI.