Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Powiadomienia systemowe

Sesja wygasła!
Sesja wygasła!
Sesja wygasła!

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: 13C NMR spectroscopy

Sortuj według:

Ogranicz wyniki do:

Exploration of the possibility of combined HS-GC-MS and 13C NMR spectroscopic investigation of the composition of the essential oils of selected sage (Salvia) species

Sajewicz M., Matlengiewicz M., Rzepa J., Wojtal Ł., Hajnos M., Waksmundzka-Hajnos M., Kowalska T.

Acta Chromatographica

2011

Vol. 23, no. 1

181--190

The objective of this study was to explore the possibility of combining headspace gas chromatography with mass spectrometric detection (HS-GC-MS) and 13C NMR spectroscopy to enhance the detectability of components of the essential oils of medicinal plants of the Salvia genus. Preliminary investigations were performed with two sage species, Salvia lavandulifolia and Salvia triloba, known for particularly abundant yields of their respective essential oils. By use of HS-GC-MS, characteristic fingerprints of the volatile fractions were obtained for plant species from two different vegetation seasons (2007 and 2008). Partial identification of the components of these volatile fractions was performed, and comparison of the chromatographic fingerprints confirmed seasonal fingerprint similarity within the same species. Preliminary 13C NMR measurements resulted in well shaped spectra with an abundance of regularly distributed signals. This suggested the possibility of using 13C NMR spectroscopy in phytochemical research, in parallel with HS-GC-MS, to enhance the detectability of volatile components of plant species belonging to this genus.

On the spontaneous condensation of selected hydroxy acids

Sajewicz M., Matlengiewicz M., Kronenbach D., Gontarska M., Kowalska T.

Acta Chromatographica

2009

Vol. 21, no. 2

259--271

In a previous study we provided thin-layer chromatographic, polarimetric, and other experimental evidence that phenylglycine can undergo easy spontaneous peptidization in abiotic aqueous media. From our unpublished results it is apparent that this behaviour is also characteristic of some other amino acids (e.g., alanine and phenylalanine). It seems highly probable that this abiotic peptidization of amino acids dissolved in aqueous media is directly linked to their ability to undergo spontaneous oscillatory chiral conversion. In our earlier research it was also shown that spontaneous oscillatory chiral conversion was characteristic not only of amino acids but also of several other classes of carboxylic acid, including profen drugs and hydroxy acids. We therefore decided to check whether selected chiral hydroxy acids — lactic acid and mandelic acid — previously recognized for their ability to undergo spontaneous oscillatory chiral conversion, could also furnish the respective polyacids. Condensation of hydroxy acids can be viewed as a reaction fully analogous with peptidization of amino acids and, hence, it seemed to us highly probable that it also can be triggered by oscillatory chiral conversion. In our study, we used thin-layer chromatography and 13 C NMR spectroscopy to check whether formation of polylactic acid and polymandelic acid occurred in stored solutions of lactic and mandelic acids. By means of polarimetry with continuous recording we provided experimental evidence that all three hydroxy acids investigated (i.e. L -(+)-lactic acid, S -(+)-mandelic acid, and R -(−)-mandelic acid) undergo continuous chiral conversion. From the thin-layer chromatographic results obtained it was apparent that — similar to the spontaneous and instantaneous peptidization of amino acids — the hydroxy acids investigated also undergo easy condensation to form the respective polyacids. 13 C NMR spectroscopy provided additional experimental confirmation of this.

Conduction Microcalorimetry and 13C NMR Spectroscopic studies on the Complexing Ability of D-erythro-L-manno-D-gluco-dodecitol with Selected Lanthanide Salts in Water Solutions

Mach M., Utzig E., Jarosz S.

Polish Journal of Chemistry

2002

Vol. 76 / nr 4

565-574

Complexing ability of D-erythro-L-manno-D-gluco-dodecitol (1) with lanthanides salts: La(NO3)3ź6H2O and PrCl3ź6H2O in water by conduction microcalorimetry and 13C NMR spectroscopy was studied. It was compared to the complexing ability of known D-galactitol (2), D-mannitol (3), and D-glucitol (4) under the same conditions.