COLLABORATIVE STUDY - DETERMINATION OF RETINOL AND CAROTENE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Seventeen laboratories participated in the analysis of 10 products for carotene and retinol by high-performance liquid chromatography. Test materials were saponified and the nonsaponifiables were extracted with petroleum ether. The extract was injected into the liquid chromatogra ph for determination of carotene at 450 nm/436 nm, using a C18 reverse d-phase column with a mobile phase of acetonitrile:methylene chloride: methanol:water (70:20:8:2, v/v). Retinol was determined at 325 nm/313 nm by using a C18 reversed-phase column with a mobile phase of methano l:water (90:10, v/v). The biological activities of retinol and caroten e expressed in international units were summed to give total activity. The repeatability (within laboratory) coefficients of variation range d from 3.46-15.65%, and the reproducibility (among laboratories) coeff icients of variation ranged from 5.34-15.77%. (C) 1997 Published by El sevier Science Ltd. All rights reserved.