Authentication of Quercus Species According to Their n-Alkanes Profile by Off-Line Combination of High-Performance Liquid Chromatography and Gas Chromatography

Abstract

© 2014, Springer Science+Business Media New York. n-Alkanes of 15 samples of acorn oil from Quercus ilex and Quercus suber have been analysed by gas chromatography. Oil was extracted in a Soxhlet glass apparatus using petroleum ether as solvent. The unsaponifiable matter was fractionated by high-performance liquid chromatography. Then, the analysis was performed on a capillary DB-5MS column (30 m × 0.25 mm i.d., 0.25 μm film thickness), with hydrogen as carrier gas and using a flame ionization detector. Eicosane was used as internal standard for quantification of individual n-alkanes. Gas chromatography-mass spectrometry (GC-MS) analysis in full scan mode was used for their identification. Ten compounds have been identified in these samples: heneicosane, docosane, tricosane, tetracosane, pentacosane, hexacosane, heptacosane, octacosane, nonacosane and triacontane. By using these compounds as chemical descriptors, pattern recognition techniques, such as principal component analysis and linear discriminant analysis, were applied to find out a suitable classification model and differentiate between Q. ilex and Q. suber genuses. The results showed that these compounds allowed the differentiation of the two genuses with a complete classification.