DETERMINATION OF MILK-PROTEINS BY CAPILLARY ELECTROPHORESIS

The determination of milk proteins by capillary zone electrophoresis ( CZE) is hampered by the adsorption of the solute on the capillary wall . The effects of pH, ionic strength of the buffer and polymeric additi ves were studied in combination with a hydrophilically coated capillar y. Optimum separations were obtained at low pH (2.5-3) in aqueous solu tions containing 6 M urea and methylhydroxyethylcellulose, resulting i n a complete separation of the serum proteins and caseins, including s ome genetic variants. The results were compared with those achieved wi th reversed-phase HPLC. With CZE, theoretical plate numbers in the ran ge 300 000-700 000 were obtained. The relative standard deviations for migration times were below 0.08% and for peak areas were 2-4%. The se paration of cow, goat and sheep milk proteins and of heat-damaged case in is reported.