title: Quantification of β-carotene, retinol, retinyl acetate and retinyl palmitate in enriched fruit juices using dispersive liquid-liquid microextraction coupled to liquid chromatography with fluorescence detection and atmospheric pressure chemical ionization-mass spectrometry.
abstract: A detailed optimization of dispersive liquid-liquid microextraction (DLLME) was carried out for developing liquid chromatographic (HPLC) techniques, using both fluorescence and atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection, for the simultaneous analysis of preforms of vitamin A: retinol (R), retinyl acetate (RA), retinyl palmitate (RP) and β-carotene (β-C). The HPLC analyses were carried out using a mobile phase composed of methanol and water, with gradient elution. The APCI-MS and fluorescence spectra permitted the correct identification of compounds in the analyzed samples. Parameters affecting DLLME were optimized using 2 mL of methanol (disperser solvent) containing 150 μL carbon tetrachloride (extraction solvent). The precision ranged from 6% to 8% (RSD) and the limits of detection were between 0.03 and 1.4 ng mL(-1), depending on the compound. The enrichment factor values were in the 21-44 range. Juice samples were analyzed without saponification and no matrix effect was found when using fluorescence detection, so calibration was possible with aqueous standards. However, a matrix effect appeared with APCI-MS, in which case it was necessary to apply matrix-matched calibration. There was great variability in the forms of vitamin A present in the juices, the most abundant ester being retinyl acetate (0.04 to 3.4 μg mL(-1)), followed by the amount of retinol (0.01 to 0.16 μg mL(-1)), while retinyl palmitate was not detected, except in the milk-containing juice, in which RP was the main form. The representative carotenoid β-carotene was present in the orange, peach, mango and multifruit juices in high amounts. The method was validated using two certified reference materials.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia, E-30071 Murcia, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Viñas
authors.forename: María
authors.initials: M
authors.lastname: Bravo-Bravo
authors.forename: Ignacio
authors.initials: I
authors.lastname: López-García
authors.forename: Manuel
authors.initials: M
authors.lastname: Hernández-Córdoba
mesh_terms: D001628:Beverages / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004224:Diterpenes; D005638:Fruit / Q000737:chemistry*; D016018:Least-Squares Analysis; D059627:Liquid Phase Microextraction / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods; D015203:Reproducibility of Results; D000084562:Retinyl Esters; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000032:analysis / Q000302:isolation & purification; D019207:beta Carotene / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D004224:Diterpenes; D000084562:Retinyl Esters; D019207:beta Carotene; D014801:Vitamin A; C014794:retinol palmitate; C009166:retinol acetate