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7

Low-Temperature Thin-Layer Chromatography with Mass Spectrometric

Detection (LT TLC-MS)

The results of the ID LT TLC-MS fingerprinting of the essential oil derived from the herbal sample of Safoia lavandulifolia (harvested in 2007) are given in Fig. 1. In Fig. l(o), we show the densitogram with bands (l)-(3) indicated by the arrows. These three bands were further instrumentally fmgerprinted, either directly by means of mass spectrometric detector, or indirectly by means of high-performance liąuid chromatograph coupled with mass spectrometric detector.

The results of the direct TLC-MS fingerprinting are shown in the three mass spectra (Figs l(a)-(c)). With complex mixtures (and essential oils fumish precisely such a mixture), the adsorption TLC can provide preliminary group separation only, dividing all constituents into the groups of similar polarity. In the described case, band 1 contains the constituents with the relatively lowest retardation factor, Rr (equal to 0.05), and hence with the highest affinity to the adsorbent and most probably, with the highest polarity also. The compounds belonging to band 2 (7?f = 0.39) are those of medium affinity to the adsorbent, and the compounds belonging to band 3 (/?f - 0.49) are those of the lowest affinity to the adsorbent. However, between bands 2 and 3, a relatively smali difference in the respective retardation coefficients is observed (A/?f(3,2> = 0.10), which suggests that these two fractions are the mixtures of structurally similar compounds, and morę precisely, that they both possibly contain different monoterpenes and/or sesąuiterpenes rather than terpenoids.

An attempt was madę to reflect on structural information contained in the respective mass spectra, additionally taking into the account the literaturę data on the presence of certain terpenes and terpenoids in Safoia lavandulifolia (see Table 1).

Visual inspection of the fmgerprints given in Figs I(a)-(c) allows a conclusion that band 1 represents a morę complex mixture of compounds than bands 2 and 3 (even, if we correctly anticipate that many signals present in the three compared spectra do not represent parent ions alone, but they largely result from fragmentation / structural transformation / clustering of the original compounds).

Further, it seems justified to expect that the fraction with the highest affinity to the adsorbent (i.e., band 1) can largely be composed of the polar oxygen-containing monoterpene and sesąuiterpene derivatives (i.e., of those with the m/z signals in the rangę from 152.23 to 210.31, and higher than 220.34, respectively; see Table 1). The still higher m/z values in band