Tocopherol analysis was performed by HPLC (Shimadzu,
Kyoto, Japan) equipped with an LC-10 AD model pump
and a SPD-10A ultraviolet (UV) detector set at 295 nm
fitted with silica column (5 μm, 4.6 250 mm). The
mobile phase was hexane/isopropanol (98.5:1.5, v/v),
and the flow rate was 0.6 mL/min. α-, β-, γ- and δ-tocopherol standards were used for quantification.