Qualitative and quantitative analysis of Teucrium polium essential oil components by GC-MS coupled with MCR and PARAFAC methods.

Abstract

Teucrium polium is a herbal plant which has curative potential and pharmacological characteristics. Therefore, establishment of accurate analytical methods for characterising its active components is of prime importance. Because of the complex nature of essential oil samples, some results of direct gas chromatography-mass spectrometry (GC-MS) analysis maybe unreliable. Therefore, GC-MS is coupled with chemometric methods to resolve experimental information taken from chromatographic peaks, and assign compounds to them more correctly. Essential oil of T. Polium of Koohbanan suburb (Kerman, Iran) was extracted by hydro-distillation. Then the T. polium essential oil was qualitatively analysed using GC-MS coupled with multivariate curve resolution (MCR), to resolve experimental information taken from chromatographic peaks, and assign compounds to them more correctly. After that, the method of parallel factor analysis (PARAFAC) was implemented to quantify the concentrations of five major components of the T. polium essential oil. The number of identified components increases from 74 using the direct method of analysis to 106 using the MCR method. It is shown that α-pinene (8.93μg/L), cis-verbenol (3.98μg/L) and myrtenal (1.02μg/L) are the most abundant components in the T. polium essential oil. By coupling GC-MS and chemometric resolution methods such as MCR-alternating least squares (ALS) and PARAFAC more information with higher precision and accuracy can be obtained from raw experimental data. Also, it is shown that by implementing the PARAFAC method on the GC-MS data, it is possible to measure the concentration of the constituents of co-eluted, overlapped or embedded chromatographic peaks.