Improved method for the simultaneous determination of whey proteins, caseins and para-κ-casein in milk and dairy products by capillary electrophoresis

A capillary electrophoresis method for the simultaneous determination of whey proteins, caseins and their degradation products, such as para-κ-casein, was proposed. The effect of several parameters (pH, ionic strength and concentration of urea in the electrophoresis buffer and applied voltage) on the analysis time and on the separation efficiency of the major milk proteins was studied. Using a hydrophilically coated capillary, in combination with electrophoresis buffer 0.48 M citric acid–13.6 mM citrate–4.8 M urea at pH 2.3, and a separation voltage of 25 kV, a complete separation of β-lactoglobulin and para-κ-casein was achieved, permitting the quantification of both components.