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.