Application of micellar electrokinetic chromatography for the separation of retinoids

The applicability of micellar electrokinetic chromatography (MEKC) using so dium dodecylsulphate (SDS) as pseudo-stationary phase for the separation of five retinoids (retinol, retinal, retinyl acetate, retinyl palmitate, reti noic acid), was investigated. The effects of the acetonitrile content, the SDS concentration, the pH and the addition of Brij 35 to the background ele ctrolyte on the migration behaviour of the retinoids were determined. It wa s found that the effective mobilities of retinol, retinal and retinyl aceta te could be easily regulated through the ACN content and the SDS concentrat ion of the BGE. The electrophoretic behaviour of the very hydrophobic retin yl palmitate was abnormal. Under various conditions this compound showed up as a late, very sharp peak. A strong indication was Found that the retinyl palmitate forms a stable, charged complex with SDS during sample preparati on. The mobility of the retinyl palmitate peak could be regulated, independ ently from the other peaks, through the Brij concentration of the BGE. Usin g a running buffer consisting of Tris-buffer (pH 8), 20 mmol 1(-1) SDS, 1 m mol 1(-1) Brij 35 and 35% (v/v) acetonitrile, a complete separation of the five retinoids could be realised in less than 20 min. (C) 2000 Elsevier Sci ence B.V. All rights reserved.