Determination of flavone C-glucosides in antioxidant of bamboo leaves (AOB) fortified foods by reversed-phase high-performance liquid chromatography with ultraviolet diode array detection

Reversed-phase high-performance liquid chromatography (RP-HPLC) with ultraviolet diode array detection (UV-DAD) was used for the simultaneous determination of four flavone C-glucosides, i.e. orientin, homoorientin, vitexin and isovitexin in several food systems fortified by the antioxidant of bamboo leaves (AOB), such as high temperature sterilized milk, sunflower seed oil and extruded rice cake for the first time. The method included extraction of flavone C-glucosides from AOB-fortified foods by methanol aqueous solution, deproteinating with saturated lead acetate solution and potassium oxalate, defatting with n-hexane and clean-up by solid-phase extraction (SPE) with Phenomenex C18 cartridges. Analytes were separated with Luna C18 5 μm 250 mm × 4.6 mm column using acetonitrile and 1% (v/v) acetic acid (pH 3.0) as mobile phase. Good results were obtained with respect to repeatability (relative standard deviation (RSD) < 2.2%) and recovery (81.4-91.8%) which fulfilled the requirements defined by European Union (EU) legislation. The total amounts of four flavone C-glucosides were 12.56 μg/100 mL, 881.08 μg/100 mL and 1420.83 μg/100 g dry weight in AOB-fortified sterilized milk, sunflower seed oil and extruded rice cake, respectively. The method was successfully applied to the analysis of flavone C-glucosides in AOB-fortified samples. The optimized procedure could also be referenced for the separation of flavone C-glucosides in other fortified foodstuffs.