Simultaneous determination of lipophilic vitamin esters using square-wave voltammetry at the glassy carbon electrode

Abstract

Simple and rapid voltammetric method for simultaneous determination of all-trans-retinyl acetate (RAc) or all-trans-retinyl palmitate (RPa) and alpha-tocopheryl acetate (alpha-TOAc) has been proposed. The respective method was based on the anodic oxidation of the compounds of interest by square-wave voltammetry in acetone with 0.1 mol L-1 LiClO4 at the glassy carbon electrode. The procedure was also beneficial with respect to simple dissolution of sample directly in the supporting electrolyte. The all-trans-retinyl acetate could be quantified in two linear ranges (3.1-140 µmol L-1 and 140-400 µmol L-1) and alpha-tocopheryl acetate in linear range 5.3-400 µmol L-1 with detection limits of 0.9 µmol L-1 RAc (or 0.8 µmol L-1 RPa) and of 1.6 µmol L-1 alpha-TOAc. Selected commercial cosmetic products were analysed achieving satisfactory recoveries.