Tracing possible structural asymmetry of silica gel used for precoating thin-layer chromatography plates

Sajewicz, Mieczysław; Hauck, H.F.; Drabik, Gabriela; Namysło, Ewa; Głód, Bronisław K.; Kowalska, Teresa

doi:10.1556/jpc.19.2006.4.4

Cited by 16 publications

(12 citation statements)

References 4 publications

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“…In order to demonstrate intermolecular interactions between the chiral elements of stationary phase and the chiral analytes that result in the twodimensional separations of the scalemic (or racemic) mixtures of ibuprofen and naproxen (as discussed, e.g., in papers), [1,2,5] we selected among the simplest chromatographic systems possible. Two different stationary phases were used in our experiment, namely (i) plain silica gel and (ii) silica gel impregnated with L-arginine.…”

Section: Resultsmentioning

confidence: 99%

“…Upon our earlier results obtained with use of the scanning densitometer and presented in papers, [1,2] it could be concluded that the main effect of the silica gel chirality was the horizontal enantioseparation of the …”

Section: Introductionmentioning

confidence: 80%

“…In this paper [1] we published the results from examination of the silica gel samples by means of the spectroscopy of circular dichroism (CD), and it came out thatagainst a popular and widespread conviction -silica gel is not amorphous, but chiral. Chirality of silica gel combined with the two-dimensional effective diffusion (taking place in the planar chromatography systems and for obvious reasons absent from the chromatographic columns) results in the horizontal contribution to the enantioseparation of the racemic and scalemic mixtures, as it was shown upon the selected examples of 2-arylpropionic acids (2-APAs) in literature.…”

Section: Introductionmentioning

confidence: 99%

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Use of Video Densitometry and Scanning Densitometry to Study an Impact of Silica Gel and L‐Arginine on the Retention of Ibuprofen and Naproxen in TLC Systems

Sajewicz

Gontarska

Dąbrowa

et al. 2007

Journal of Liquid Chromatography & Related Technologies

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In our earlier articles, we demonstrated the phenomenon of the two-dimensional enantioseparation of the selected 2-arylpropionic acids (2-APAs) in the onedimensional thin-layer chromatographic mode, yet our measuring results originated from the classical scanning densitometry only. A basic precondition of the discussed phenomenon is the omnipresence of the two-dimensional effective diffusion in planar chromatography. However, one should anticipate an action of the two different-and apparently chiral -elements, one responsible for the vertical enantioseparation (in the direction of the mobile phase migration) and another one responsible for the horizontal enantioseparation (inducing deviation of the chiral analytes' migration tracks from the vertical). In the investigated chromatographic systems two chiral elements are in fact present. One chiral element is the microcrystalline silica gel layer and the other one is L-arginine as the impregnating chiral selector. Upon our earlier results originating from the scanning densitometry, it could be deduced that the crystalline chirality of silica gel is responsible for the horizontal enantioseparation, and the molecular chirality of L-arginine is responsible for the vertical separation. In this study, we confirm our earlier findings in a more immediate way, using the flatbed video densitometry to record the pictures of the whole chromatograms and also those of the individual chromatographic spots of ibuprofen and naproxen. We combine these results with the data obtained from the classical scanning densitometry to monitor the discussed enantioseparations by means of the concentration profiles of the respective antimers. Combination of the results originating from the video and the scanning densitometry allows a deep enough insight in the chromatographic behavior

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

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Use of Video Densitometry and Scanning Densitometry to Study an Impact of Silica Gel and L‐Arginine on the Retention of Ibuprofen and Naproxen in TLC Systems

Sajewicz

Gontarska

Dąbrowa

et al. 2007

Journal of Liquid Chromatography & Related Technologies

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“…The starting point for our considerations is the fact that silica gel used for the thin-layer chromatography cannot be considered as an amorphous powder, because microcrystalline chirality thereof was demonstrated with use of the spectroscopy of circular dichroism (CD) [4]. No similar result has ever been reported for alumina used for the thin-layer chromatography, which can therefore be considered as an achiral and amorphous powder.…”

Section: Resultsmentioning

confidence: 99%

“…Lateral relocation (i.e., sidewise deviation of the analytes' migration route from linearity) has been reported in our earlier studies on the thinlayer chromatographic enantioseparation of chiral low molecular weight carboxylic acids belonging to the groups of profen drugs, amino acids, and hydroxy acids (e.g., in Refs. [4][5][6]). In Refs.…”

Section: Introductionmentioning

confidence: 99%

Specific mobility of selected phytochemicals in thin-layer chromatographic systems and its possible relevance to pharmacokinetics

Knaś

Szeremeta

Polański

et al. 2013

Acta Chromatographica

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Summary. In many publications on the thin-layer chromatographic analysis of the medicinal plant extracts, striking skewness of the separated chromatographic bands with many phytochemicals can be seen, although no attention has ever been paid to this odd mass transfer effect. In our earlier studies on the thin-layer chromatographic enantioseparation of certain low molecular weight carboxylic acids, lateral relocation thereof (i.e., the side-wise deviation of their migration route from linearity) was registered. Then we found out that lateral relocation was observed with these analytes only, which structurally resembled molecular rotors. In this study, we investigate the role played by the thin-layer chromatographic stationary phases in lateral relocation of botanically relevant molecular rotors. Thus, three carboxylic acids were selected as the test analytes, all of them resembling molecular rotors and abundantly present in the medicinal plant extracts. We selected two most popular thin-layer chromatographic stationary phases also, i.e., silica gel (characterizing with microcrystalline chirality) and alumina (achiral). Lateral relocation of the test analytes was observed on the silica gel stationary phase only. A conclusion was drawn that the chiral stationary phase makes a complementary contribution to lateral relocation (along with the propeller-like molecular structure of the analytes). In our view, specially devised thin-layer chromatographic systems can prove a convenient nano-platform for future investigation of the drug transport patterns, advantageous in the pharmacokinetic studies.

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8.16 Chromatographic Separations and Analysis: Chiral Separations by Thin Layer Chromatography

Polak

2012

Comprehensive Chirality

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Tracing possible structural asymmetry of silica gel used for precoating thin-layer chromatography plates

Cited by 16 publications

References 4 publications

Use of Video Densitometry and Scanning Densitometry to Study an Impact of Silica Gel and L‐Arginine on the Retention of Ibuprofen and Naproxen in TLC Systems

Use of Video Densitometry and Scanning Densitometry to Study an Impact of Silica Gel and L‐Arginine on the Retention of Ibuprofen and Naproxen in TLC Systems

Specific mobility of selected phytochemicals in thin-layer chromatographic systems and its possible relevance to pharmacokinetics

8.16 Chromatographic Separations and Analysis: Chiral Separations by Thin Layer Chromatography

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