An improved high-performance liquid chromatographic method for simultaneous determination of tocopherols,...

An improved normal phase high performance liquid chromatographic (NP-HPLC) method was developed for simultaneous quantification of eight vitamin E isomers (α-, β-, γ- and δ-tocopherols and α-, β-, γ- and δ-tocotrienols) and γ-oryzanol in rice. A complete separation of all compounds was achieved within 25 min using an Inertsil CN-3, SIL-100A 5 μM (4.6 mm × 250 mm) column and an isocratic elution system of hexane/isopropanol/ethylacetate/acetic acid (97.6:0.8:0.8:0.8, v/v/v/v) at a flow rate varying from 0.7 to 1.5 mL min(-1). A linear correlation coefficient (r(2)>0.99) and high reproducibility were obtained at concentrations ranging 0.05-10 μg mL(-1) for vitamin E isomers and 0.5-500 μg mL(-1) for γ-oryzanol. This method proved to be rapid, accurate and reproducible.