An improved high-performance liquid chromatographic method for simultaneous determination of tocopherols, tocotrienols and γ-oryzanol in rice

An improved normal phase high performance liquid chromatographic (NP-HPLC) method was developed for simultaneous quantification of eight vitamin E isomers (alpha-, beta-, gamma- and delta-tocopherols and alpha-, beta-, gamma- and delta-tocotrienols) and gamma-oryzanol in rice. A complete separation of all compounds was achieved within 25 min using an Inertsil (R) CN-3, SIL-100A5 mu M (4.6 mm x 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 mu g mL(-1) for vitamin E isomers and 0.5-500 mu g mL(-1) for gamma-oryzanol. This method proved to be rapid, accurate and reproducible. (C) 2011 Elsevier B.V. All rights reserved.