Determination of the stability of caseinoglycomacropeptide in a cosmetic lotion by use of capillary zone electrophoresis with a coated capillary

A capillary zone electrophoretic method is described for the determination of a caseinoglycomacropeptide. The optimized conditions employed a poly(vin yl alcohol)coated capillary and 50 mM phosphate buffer at pH 2.5 to enable baseline separation of several glycoforms. The method was validated and per formance was good in terms of precision (both peak area and migration time) , selectivity, linearity, and accuracy. The method was used to determine ca seinoglycomacropeptide (2 % w/w) in a cosmetic lotion. The validated method was finally used to monitor the stability of this caseinoglycomacropeptide in the cosmetic lotion over a period of four months.