Determination of Linalool in Essential Oils by SPME-GC-MS: Using the Internal Standard Method

A novel undergraduate analytical chemistry experiment involving the identification and quantification of linalool in essential oils was developed. The experiment uses the internal standard method with headspace solid phase microextraction (SPME) and gas chromatography--mass spectrometry (GC-MS). This method is applicable to any linalool-containing essential oil sample but could be expanded to quantify other components. Initial experiments demonstrated the effectiveness of the internal standard method, with the regression analysis of the internal standard calibration curve having excellent linearity (R[superscript 2] [greater than or equal to] 0.98) compared to external standard calibration (R[superscript 2] < 0.50). Several essential oils were tested, and the quantified concentrations were typically within 20% of the expected concentrations from manufacturer data or literature results. With >30% linalool, lavender oil was found to contain the highest concentration of linalool compared to all oils tested. This experiment introduces method development, SPME, GC-MS, and the internal standard method to sophomore and junior level chemistry students. This lab was used in analytical and organic chemistry classes but could be used with any students interested in quantitative instrumental analysis methods. In a survey of three separate groups of students who performed the lab, most students responded that the experiment provided them a better understanding of SPME, GC-MS, and the internal standard calibration method.