Liquid chromatographic method for the determination of lutein in milk and pediatric formulas

A simple and rapid method has been developed for routine compliance testing of lutein in pediatric formulas. Following a mild saponification procedure (70 °C for 10 min) demonstrated to be benign to lutein, lipophilic components were partitioned by a single extraction into hexane:diisopropyl ether (75:25 v/v) and concentrated in mobile phase. Baseline chromatographic separation of lutein and zeaxanthin (internal standard) was achieved using a C30 column and isocratic elution with methanol:dichloromethane (70:30 v/v). Lutein concentration was quantitated against zeaxanthin, which corrected for incomplete extraction recovery. Performance parameters assessed included recovery (101–108%) and repeatability (2.2% RSD). The method was applied to the analysis of lutein-supplemented pediatric formulas, unsupplemented milk powders, and bovine and human milk.