Determination of fat-soluble vitamins in a pharmaceutical dosage form by solid-phase extraction and reversed-phase liquid chromatography

A rapid and precise method for the determination of fat-soluble vitamins from a water-based multivitamin mixture was developed utilizing solid-phase extraction and reversed-phase high-performance liquid Chromatography (HPLC). Cholecalciferol. α-tocopherol acetate, and retinol palmitate were extracted in a single stage from the matrix using Bond Elut C18 columns The vitamins were then chromatographed on a Hypersil 5-μm C18 column, using a water; methanol gradient, and quantified simultaneously using individual UV absorption maxima. The recovery of added analytes varied from 92.6 to 100.6%. The assay coefficient of variation was 1.7–2.7%. The sample preparation method and HPLC assay described here are practical for pharmaceutical quality control purposes.