Determination of phenolic antioxidants in vegetal and animal fats without previous extraction by dilution with n-propanol and micellar liquid chromatography

Abstract

A simple and rapid HPLC method for the determination of phenolic antioxidants (propyl and octyl gallates, tert-butylhydroquinone and 3- tert-butyl-4-hydroxyanisole) in sunflower, corn and olive oils, margarine, lard and butter oil is described. The samples are diluted with n-propanol, filtered and injected; solutions containing 30% (w/w) sample can be injected. The analytes are separated with a C18 column and a micellar mobile phase containing 0.1 M SDS, 2.5% n-propanol and 10 mM phosphate of pH 3, and detected at 290 nm. Calibration curves are linear ( r > 0.9999) and the limits of detection range from 0.2 to 1.3 ng, which correspond to antioxidant concentrations well below the levels allowed in food. Mean recovery and overall method reproducibility, as relative standard deviation, for all the samples spiked with 200 μg g −1 is (100 ± 2)% ( n = 24).