Application of factorial design and response surface methodology to the analysis of bovine caseins by capillary zone electrophoresis

Central composite design and response surface methods were applied to optimise and assess the robustness of a capillary zone electrophoresis method for the separation of bovine caseins. Buffer pH, running voltage and polymeric additive buffer concentration were the parameters selected for this study. Successful results were obtained at 18.5 kV, with 10 mM phosphate buffer at pH 3.0 with 0.05% (w/v) hydroxypropyl methyl cellulose. Under these optimised conditions αs-casein (CN), β-CN and κ-CN and the various phosphorylation states of the αs1-CN and αs2-CN, as well as, some genetic variants of β-CN (A1, A2 and B) were well separated.