Today plant based products, essential oils, plant extracts, natural

Today plant based
products, essential oils, plant extracts, natural resins and their preparations
have a wide range of applications mainly in perfume and cosmetic industry, in
food technology, in aroma industry and in pharmaceutical industry. This large
spectrum of uses stimulated studies on natural products. The methods used in
the analysis of plants that started at the end of the 19th century, only allowed
investigations on crystalline constituents isolated from these extracts.
Subsequent developments on vacuum distillation techniques provided the possibility
to determine the volatile components of these extracts. Along with the
developments in extraction techniques, the development of chromatographic techniques
primarily with planar chromatography (thin layer chromatography (TLC)) and other
novel analytical methods were introduced to the benefit of scientists. Gas chromatography
(GC) in the 1950’s had opened a new dimension in the analysis of volatile compounds.
In the meantime high performance liquid chromatography (HPLC) was introduced
for the fractionation and isolation of more polar and non-volatile compounds. The
combination of gas chromatography and mass spectrometry (GC-MS) allows the
rapid identification of not only volatile components but also plant extracts,
by comparing their mass spectra with available libraries which build up with
reference substances recorded under the same experimental parameters. The same
principle has been applied in the last decade for liquid chromatography and
mass spectrometry (LC-MS) for non-volatile plant constituents. Moreover, the
invention of chiral stationary phases for gas chromatography, mostly based on cyclodextrins,
has facilitated the identification of the enantiomeric composition of the
isolated substances, especially in essential oils. Simultaneously, the advances
in spectroscopic methods such as mass spectrometry (MS) and nuclear magnetic
resonance (NMR) spectroscopy, have increased the speed of the identification
and structure elucidation of natural products.