摘要:

A review is given on the quantitative structure-retention relationship (QSRR) in TLC. The establishment of QSRR equations is described, which is based on physico-chemical parameters, non-specific parameters, topological indices, and a combination of physico-chemical parameters. The application of QSRR for prediction of retention, determination of lipophilicity, evaluation of some physico-chemical parameters of chemicals, evaluation of biological activity of compounds, and explanation of separation mechanisms are also reviewed.

ISSN:1082-6076    

DOI:10.1081/JLC-100101639

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

We investigated the dependence between retention of five different test solutes and the mobile phase composition in thin-layer chromatographic systems with the chemically bonded 3-cyanopropyl stationary phase and binary 2-propanol - n-hexane eluents. Then, we calculated regression parameters for the selected three models of solute retention (applicable to the adsorption liquid chromatography mode), first upon all 36 experimental data points and, then, upon a restricted number of four experimental data points. Finally, the relevant conclusions were drawn regarding efficiency of the retention models considered in predicting solute retention (and consequently, in optimization of separation selectivity) based upon the results of an absolutely minimal introductory experiment.

ISSN:1082-6076    

DOI:10.1081/JLC-100101640

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The lipophilicity of 15 2-hydrazinothiazolic derivatives was studied by reversed phase thin layer chromatography on silica-C8 plates with methanol-water mobile phase. The studied compounds have shown antifungal activity againstLepidium sativum, and the corresponding inhibition values that measure their mitodepresive activity are given.

ISSN:1082-6076    

DOI:10.1081/JLC-100101641

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Selected amino acids have been separated into their enantiomers by thin layer chromatography on a chiral stationary phase. A new valence optical topological index (Iνopt) and valence optical Gutman index (Mν2opt) are proposed which enable distinction between isomers ofLandDconfiguration.

ISSN:1082-6076    

DOI:10.1081/JLC-100101642

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The retention behaviour of some phenols and aromatic amines on CN and Diol precoated high-performance thin-layer chromatographic plates was examined using normal-phase eluent systems: polar modifier (2-propanol, ethyl acetate, ethyl methyl ketone, dioxane, tetrahydrofuran or diisopropyl ether) in n-heptane. The results were compared with the retention parameters of investigated compounds obtained in the same eluent systems on bare silica. The results are presented by the comparison of δRMvalues for pairs of positional isomers and by the RM Ivs. RM IIrelationships of phenols and anilines for CN-silica - silica, diol-silica - silica and CN - diol stationary phases.

ISSN:1082-6076    

DOI:10.1081/JLC-100101643

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The Rfvalues of ten antioxidants, namely several UOP, Permanax, Antozite, etc., have been calculated on the basis of their structures. The Rfcalcvalues have been compared with the experimental Rfvalues, obtained on reversed phase TLC plates. The variance of the calculated data around the experimental Rfvalues is 4.10−4. The approach allows a positive identification without reference substances or with a limited number of standards, which is the structure that gives Rfcalcvalues close to the Rfof the sample spots. Some considerations on the probable retention mechanism are also given.

ISSN:1082-6076    

DOI:10.1081/JLC-100101644

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A rational selection of a restricted set from fifteen available chromatographic systems for the separation of flavonoids and phenolic acids identified in the methanolic extract ofRhamni cathartici fructusis discussed. Series of mathematical techniques for the evaluation of solvents and solvent combinations in thin-layer chromatography of flavonoids and phenolic acids have been investigated. The chromatographic systems are classified according to their mutual resemblance by numerical taxonomy techniques. The selection criterion in the groups, obtained by numerical taxonomy classification, is the information content or discriminating power. The numerical taxonomic and information theoretical selection procedures are compared and their respective advantages and disadvantages discussed.

ISSN:1082-6076    

DOI:10.1081/JLC-100101645

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The direct resolution of nineteen structurally related racemic flavanones was evaluated by reversed-phase planar chromatography using both home-made microcrystalline cellulose triacetate (MCTA) layers and mobile phase modifiers, such as β-cyclodextrin and bovine serum albumin, on commercially available Sil C18-50/UV254plates. Except for the two glycosides, 5-methoxy-, 7-hydroxy- and 5-hydroxy-7-methoxyflavanone, the enantiomers of other flavanones were all resolved by at least one of the three chiral phases tested. Densitograms of racemic flavanones were measured on MCTA layers developed with alcohol-water mixtures and on Sil C18-50/UV254plates after elution with chiral mobile phases.

ISSN:1082-6076    

DOI:10.1081/JLC-100101646

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

High-performance thin layer chromatography (HPTLC) was used to determine neutral lipids in the cecal contents and mucosa of domestic chicks and ICR mice, and in the cecal mucosa of chicks infected withZygocotyle lunata(Trematoda). Silica gel plates were developed with petroleum ether-diethyl ether-acetic acid (80:20:1) mobile phase, and neutral lipids were detected using phosphomolybdic acid reagent. The cholesteryl ester fraction was quantified by HPTLC-densitometry. HPTLC analysis showed differences in the neutral lipid composition of the cecal contents of chicks, compared with the cecal contents of ICR mice. There were differences in neutral lipid profiles between the uninfected cecal mucosa of chicks and chick cecal mucosa infected withZ lunata. These findings showed that this parasite can alter the neutral lipid composition of the host cecal mucosa.

ISSN:1082-6076    

DOI:10.1081/JLC-100101647

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The interaction of twelve 8-substituted-2'-deoxyadenosine and seventeen 5-substituted-2'-deoxyuridine derivatives with gamma-cyclodextrin (GCD) was studied by charge-transfer chromatography carried out on reversed-phase layers and the elative strength of interaction was calculated. GCD formed inclusion complexes with the majority of drugs modifying in this manner the lipophilicity of the uncomplexed molecule. The capacity of Antiviral nucleosides to form inclusion complexes differed considerably depending on their chemical structures.

ISSN:1082-6076    

DOI:10.1081/JLC-100101648

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor