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Differences Among Epilobium and Hypericum Species Revealed by four IR Spectroscopy Modes: Transmission, KBr Tablet, Diffuse Reflectance and ATR
Author(s) -
Kokalj Meta,
Kolar Jana,
Trafela Tanja,
Kreft Samo
Publication year - 2011
Publication title -
phytochemical analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 72
eISSN - 1099-1565
pISSN - 0958-0344
DOI - 10.1002/pca.1315
Subject(s) - attenuated total reflection , chemistry , spectroscopy , principal component analysis , diffuse reflectance infrared fourier transform , botany , infrared spectroscopy , hypericum , biology , physics , artificial intelligence , biochemistry , organic chemistry , quantum mechanics , photocatalysis , computer science , catalysis
Quality control of dried plant material in assessments of suitability of herbal medicinal products is of extreme importance. Commonly used procedures for identification of species are time consuming and expensive. The development of multivariate statistical methods has enabled application of vibrational spectroscopy for establishing plant species membership. Objective To determine which infrared spectroscopy mode gives most informative spectra for plant species identification. Methodology Different modes of infrared spectroscopy were applied for investigation of differences among Epilobium and Hypericum species: diffuse reflectance (DR), attenuated total reflectance (ATR), direct transmission of whole leaves and KBr tablet transmission with comminuted leaves. The same chemometrical methods were applied to all spectra. The informative wave numbers were chosen by one‐way analysis of variance. Afterwards the colinearity was reduced with principal component analysis. In the final step the species identification was determined with discriminant analysis. Results Transmission and diffuse reflectance mode did not give satisfactory results. Best results for discrimination among Epilobium species were obtained with ATR mode (98%), while best results for Hypericum species were obtained with KBr transmission mode (97%). This might be explained by the morphological properties of the two genera. Epilobium species differ in distribution and morphology of trichomes on the surface of the leaves. Hypericum species differ in structures and secondary metabolites in the interior of the leaves. Conclusion For best results in using infrared spectroscopy for plant species identification in quality control, the morphological properties of plant material should be taken into consideration. Copyright © 2011 John Wiley & Sons, Ltd.