Identification and Quantification of Carotenoids Including Geometrical Isomers in Fruit and Vegetable Juices by Liquid Chromatography with Ultraviolet−Diode Array Detection

Abstract

A method was established for the identification and quantification of carotenoids including geometrical isomers in fruit and vegetable juices by liquid chromatography with an ultraviolet−diode array detector, using a C₁₈ Vydac 201TP54 column. The mobile phase used was the ternary methanol mixture (0.1 M ammonium acetate), tert-butyl methyl ether and water, in a concentration gradient, and a temperature gradient was applied. Retinol palmitate was added as an internal standard. An extraction process (ethanol/hexane, 4:3, v/v) was performed, followed by saponification with diethyl ether/methanolic KOH (0.1%, w/v, BHT) (1:1, v/v) for 0.5 h at room temperature. Seventeen different (cis and trans) carotenoids were identified by UV−vis spectra and retention times in HPLC in the juices analyzed. The analytic parameters show that the method proposed is sensitive, reliable, accurate, and reproducible. Keywords: Carrot juice; cis−trans carotenoids; citric juice; Citrus sinensis; food analysis; liquid chromatography