Tocopherols in Seeds and Nuts: QuEChERS Extraction, HPLC Separation, and Fluorescence Detection

A student experiment that uses QuEChERS (quick, easy, cheap, effective, rugged, and safe) methodology for extraction and HPLC for quantitative determination of tocopherols from seeds and nuts is described here. Chromatographic separation is achieved by using a pentafluorophenyl stationary phase which gives enhanced separation of the tocopherols when compared to the more common C18 reversed phase. Sensitive detection is by fluorescence which is also compared to the less sensitive and less selective UV-vis method. The experiment provides students with valuable laboratory skills including sample preparation and cleanup using QuEChERS methodology and quantitative analysis using the method of internal standards by HPLC. Subsequently, the experiment provides an opportunity for students to consolidate their learning of the key theoretical concepts including liquid chromatography separation mechanisms and relevant sample preparation and cleanup methods for complex samples. The experiment is designed for upper-division undergraduate analytical chemistry students.