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and protecting them by plastic foil was meant to prevent evaporation of the volatile essential oil components from the plates.

Application of LT TLC-densitometry was an indispensable initial step in each of the two novel procedures introduced in this study. Firstly, it enabled group separation of a complex mixture of the volatile compounds contained in the investigated essential oil samples into several less complex mixtures. Secondly, it allowed localization of the separated chromatographic bands on the piąte surface, which is particularly important with the colorless analytes. Consequently, positions of individual chromatographic bands could be marked on the adsorbent surface, in that way indicating areas for the consecutive elution with use of the TLC-MS interface.

Low-Temperature Thin-Layer Chromatography with Mass Spectrometric

Detection (LT TLC-MS)

The first chromatographic modę assumed in this study consisted in a direct elution of a given band from the chromatographic piąte with use of the TLC-MS interface (CAMAG, Muttenz, Switzerland), which enabled an introduction of a given band from the chromatographic piąte to mass spectrometer. This modę is referred to as the low-temperature thin-layer chromatography with mass spectrometric detection (LC TLC-MS) and it has been devised to fmgerprint the preliminarily fractionated essential oils originating from the dried and powdered sagę samples [8].

In this study, elution was carried out at ambient temperaturę with use of methanol (its flow ratę equal to 0.2 mL min'¹). The eluate was directly introduced to the Varian 500-MS model mass spectrometer (Varian, Harbor City, CA, USA) and the samples were analyzed in the ESI modę (fuli ESI-MS scan, positive ionization, spray chamber temperaturę 45°C, drying gas temperaturę 150°C, drying gas pressure 25 psi, capillary voltage 70 V, needle voltage 5 kV). Varian MS Workstation v. 6.9.1 software was used for data acquisition and processing.

Low-Temperature Thin-Layer Chromatography-Liquid Chromatography with

Mass Spectrometric Detection (LT TLC-LC-MS)

The second chromatographic modę is for the first time proposed in this study and it also aims at mass spectrometric fmgerprinting of the essential oils derived from the sagę species. Owing to the TLC-MS interface, we were able to develop the two-dimensional liquid