Quantitative analysis of essential oils from rosemary in virgin olive oil using Raman spectroscopy and chemometrics

In this work, virgin olive oil mixed with essential oils from rosemary has been analyzed by means of Raman spectroscopy. First of all, experimental design has been employed in order to define the Raman spectroscopy's parameters, final measuring conditions were: acquisition time of 30?s, five accumulations, and the intensity of the laser power at 75?mW. The Raman spectra were initially measured at full range (1503000?cm-1), but a narrower window assured faster accumulations and more accurate predictions. The calibration solutions of eucalyptol and camphor in olive oil were prepared following a central composite design and different spectra pre-processing algorithms were evaluated. To conclude, essential oils obtained by means of Supercritical Fluid Extraction, Ultrasounds, and hydrodistillation were mixed with virgin olive oil and quantified with Raman spectroscopy. Predicted concentrations of the olive oil mixtures were compared with concentrations obtained for the same samples by a Comprehensive Two-Dimensional Gas Chromatographic (GC?x?GC) method. Copyright (c) 2011 John Wiley & Sons, Ltd.