117828241

Low-Temperature TLC-MS of Essential Oils from Five Different Sagę (Sa/wa) Species

Mieczysław Sajewlcz, Łukasz Woftal, Michał Ha|nos, Monika Waksmundzka-Hajnos, and Teresa Kowalska*

Key Words

Low-tem per eture TLC-MS Essential oils Terpenes and terpenolda Salvl* sp.

Summa ry

In a prcvious paper we discussed tbe possibility of fractionation tbe essential oils of different sagę species by low-temperature prepara-five layer chromatograpby (PLC), followed by preparative Lsolation of tbe contents of eacb fraction and furtber analysis by GC-MS. In tbat way we atfempted to emphasize tbe practical usefulness of low-temperature p la nar chromatograpby for investigation of volatile compounds. In tbis study, we eiplore a possibility of fractionating essential oils contained in tbe different sagę species by low-tempera-ture anatytical TLC followed by direct mass spectrometric analysis of tbe separated fractions. Tbis objective can be achieved by TI/C-MS witb on-line transfer of tbe eluted fractions. The densi-tograms obtained from five different sagę species (Le., S. Iavajtduli-folia, S. s lamin ea, S. hi ans, S. iritoha, and S. nem oroś a) are com-pared. Eacb densitogram is accompanied by mass spectra recorded for eacb peak. Videoscans of tbe cbromatograms are also presented. In tbis way multiple (ingerprints of tbe anatyzed plant materiał, eacb comprising a densitogram and a selection of mass spectra, were obtained. Advanced ebemometrie treatment of these multiple fin-gerprints can be used to reveal statistically significant differences between tbe plant species. Anatytical and cbemotaionomic advan-tages and furtber aspeefs for tbis kind of approach are discussed.

11ntroduction

The great versatility of analytical and prcparative planar chro-matography is an indisputable advantage of this long-estab-lished and maturę separation techniquc. In somc circumstances, planar chromatography can outpcrfomi other chromatographic techniques, e.g., when used to solve physicochemical tasks. Its flcxibility and robustness are basically because of its relatively simple and incxpensive equipment, the possibility of performing several analyses in parał lei on the same chromatographic piąte.

M. Sajewicz, Ł. Wojtal, and T. Kowalska. Institmc ofChemistry. Silesian Univer-sity. 9 Szkolna Street, 40-006 Katowice. Poland; M Maj nos, Department of Plur-macognosy, Medical University of Lublin. I Chodźki Str., 20-093 Lublin, Poland; and M. Waksmundzka-Ha i nos. Department of Inorganic Chemistry. Medical Unimsity of Lublin. 6 Staszica Street. 20-081 Lublin, Poland.

E-mail: [e-mail] and the two-dimensional effective diftusion, particularly helpful in enantiomer separations, as discussed elsewhere [ 1].

In a scries of publications [2-4], very interesting results were presented dealing with separation of volati!e compounds of botanical origin (basically essential oils) by low-temperature TLC. Although gas chromatography is the separation technique of choice for volatile compounds, good performance of low-temperature TLC has been convincingly demonstrated. It was shown that silica gel with its strong adsorptive power cffective-ly immobilizes essential oil constitucnts on the stationary phase surfacc; these can then be further scrutinized off-line at room temperaturę by usc of a variety of instrumental techniques.

In a previous publication 15], we introduced the low-temperature variant of preparative layer chromatography (PLC) for separation of fractions of the essential oils of five sagę (Salvia) species, followed by cxtraction of these fractions from the silica gel layer and ultimate analysis of each fraction by tandem GC-MS. To this effect, we first established separation condi-tions for analytical low-temperature planar chromatography; we then tested the same conditions for PLC. Understandably, transfer of working conditions from TLC to PLC resulted in deterio-ration of the separation. Our approach also invołved two separation tcchniqucs, PLC and GC-MS [5],

An attractivc possibility of using mass spectrometric detection in TLC has recently been described [6-8). The separated chromatographic bands can bc eluted from the chromatographic piąte (by usc of a TLC-MS intcrface) directly into the mass spectrometer. Por samples with fcw componcnts, fuli separation of single compounds and, hcnce, recording of single mass spectra is possible. With complex mixtures, thin-layer fractionation into less complex mixturcs is possible, and the mass spectrometric outeome is in the form of the fingerprints charactcristic of a given fraction. These fingerprints can, in the next step of the multi-stage study, undergo advanccd chemometric treatment with the objective of revealing statistically significant differ-ences between the individual plant species. We therefore decid-ed to replace low-temperature PLC fractionation of the essential oils of the sagę species then GC-MS fingerprinting of the iso-lated fraction by the tandem TLC-MS approach.

DOI: 10.1556/JPC.23.2010.4.6

270 Journal ot Planar Chromatography 23 (2010) 4.270-276 '    0933-41737$ 20.00 & Akaóśmiai Kiadó. Budapest