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spectrometric) in parał lei. The obtained instrumental signals can further be evaluated and compared (e g., for chemotaxonomic, quality assurance, or other purposes) with use of chemometric techniques, as it was indicated, e g., in paper [9].

The aim of this study was to repeatedly apply the one-dimensional system (ID LT TLC-MS) to the analysis of the essential oil derived from Salvia lewandulifolia and to compare the obtained results with those originating from a two-dimensional liquid chromatographic system making use of the TLC-MS interface, and proposed for the first time in this study (2D LT TLC-LC-MS). In order to circunwent the necessity of using gradient modes of the gas chromatographic or high-performance liquid chromatographic separation of a complex mixture, we proposed the preliminary thin-layer chromatographic group separation of such a mixture with the LT TLC system coupled off-line through the TLC-MS interface with the high-performance liquid chromatograph equipped with mass spectrometric detector. In that way, we managed to propose a new 2D LT TLC-LC-MS system and on the selected example of the essential oil derived from the Salvia lewandulifolia species, we compared its performance with that of the simpler ID LT TLC-MS system. The choice of Salvia !avandidifolia in this study was due to the recognized curative performance of the plants originating from the Salvia genus, and also due to the high yields of essential oil which can be derived from this particular species.

EXPERIMENTAL

Materials and Reagents

Sample of the Salvia lavanduIifoIia species was harvested in the Pharmacognosy Garden of the Medical University, Lublin, Poland, on August 20th, 2007. The plant materiał comprised all parts of the plant (i.e., roots and the aerial parts) and it was dried for 40 h in an oven with a forced air flow at 35 to 40°C. Then the obtained dry materiał was stored in the deep-freeze compartment of reffigerator until the commencement of the analysis. Finally, 50 g of the plant materiał was weighed and powdered in a porcelain mortar. Three replicates of the sagę sample were processed in an identical way.

Methanol, toluene, and ethyl acetate used for experiments were of analytical purity grade and manufactured by POCh (Gliwice, Poland).