Planta Med 2019; 85(18): 1409
DOI: 10.1055/s-0039-3399688
Abstracts of Short Lectures
Short Lectures Monday, September 02, 2019
Short Lectures B: Analytical Methods for Quality Control of Herbal Medicinal Products
© Georg Thieme Verlag KG Stuttgart · New York

Quantum mechanical modeling of NIR spectra of thymol

J Grabska
1  University of Innsbruck, Institute of Analytical Chemistry and Radiochemistry, Innrain 80-82, 6020 Innsbruck, Austria
,
KB Bec
1  University of Innsbruck, Institute of Analytical Chemistry and Radiochemistry, Innrain 80-82, 6020 Innsbruck, Austria
,
CW Huck
1  University of Innsbruck, Institute of Analytical Chemistry and Radiochemistry, Innrain 80-82, 6020 Innsbruck, Austria
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Publikationsverlauf

Publikationsdatum:
20. Dezember 2019 (online)

 
 

Near-infrared (NIR) spectroscopy is a major analytical tool with marked importance in various applications including the qualitative and quantitative analysis of herbal medicines. Yet, the physical background for the measured spectra routinely remains un-interpreted. Quantum mechanical calculations are capable of providing deep and independent insights and form a strong support for applied spectroscopy. An example of thymol [1] is presented here, an important constituent of a traditional herbal medicine Thymi herba.

NIR spectra of thymol in dependence of the sample state (solid, melted and soluted) and concentration (for soluted sample) were analyzed. Patterned spectral changes were observed, indicating that the differences between the bands in their sensitivity to the intermolecular interactions are reflected in the quantitative models. The analysis of PLS regression coefficients vector in the quantification of thymol content in Thymi herba based on NIR spectroscopy was conducted. Surprisingly, the vibrations which are the most significant spectra forming factors and which are the most sensitive to the chemical surrounding (i.e. those of OH group) do not correlated well with the sample content.

This work was supported by the Austrian Science Fund (FWF), P32004-N28.

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