High performance liquid chromatographic analysis of cholesterol in milk

A method was developed for analysis of cholesterol in whole milk powder and commercial liquid milk products. High performance liquid chromatography employed a nonaqueous reversed phase chromatographic system. Sample preparation was by saponification with methanolic potassium hydroxide followed by extraction with ether. Potential interfering substances were removed prior to injection by a simple clean-up procedure using a silica gel Sep-pakTM. The chromatographic system included a carbon-18 column with a hexane/isopropanol mobile phase and detection at 205 nm. Method validation and recovery studies using carbon-14 labeled cholesterol indicated excellent performance.