Analysis of beta-carotene in medical food by liquid chromatography with matrix solid-phase dispersion

A liquid chromatographic method is described for analysis of beta-carotene in medical food. The nutrient is extracted from medical food without saponification by matrix solid-phase dispersion and quantitated by isocratic normal-phase chromatography with a Si 60 column and a mobile phase of hexane containing 0.125% (v/v) isopropyl alcohol. The limit of quantitation is 0.02 microgram/mL at 436 nm. Standard response was linear over the concentration range of 0.02-1.0 microgram/mL (r2 = 0.99998). Recoveries were determined on a zero control reference material containing added beta-carotene at various levels. Recoveries averaged 91.2% (n = 25) with coefficients of variation from 0.50 to 3.10%. The method provides a rapid, specific, sensitive, and easily controlled assay for analysis of beta-carotene in fortified medical food. In addition, retinyl palmitate can be assayed simultaneously with an in-line fluorescence detector.