The use of chemically bonded stationary phases in thin-layer chromatography-a survey

An overview is given of the literature publisned in the field of thin-layer chromatography on chemically bonded phases. Aspects which merit further attention are: quantitative analysis, organic solvent selection, stationary phase characteristics, surface modification of precoated silica plates, ion-pair chromatography and correlation of thin-layer and column chromatographic data.     

A review of chromatographic methods for determination of synthetic food dyes

The purpose of this work was to present a chromatographic methods to analyse synthetic food dyes. The following techniques has been described: thin-layer liquid chromatography (TLC), high performance thin-layer chromatography (HPTLC), traditional column chromatography, high performance liquid chromatography (HPLC), include: ion-pair chromatography (HPLC IP), reversed phase chromatography (RP HPLC) and high performance ion chromatography.     

Investigation of some modes of flat-bed chromatography

A comparison of different chromatographic methods is presented: column liquid chromatography (CLC), thin layer chromatography (TLC), and continuous-elution flat-bed chromatography (CEFBC), which is in fact a combination of the first two methods. In CEFBC a sample is applied to a sorbent layer in a steady flow of eluent, and the components are detected directly on the layer, or immediately upon leaving it, during the separation process. It is shown that evaluation of the separation processes in CEFBC is best accomplished in terms of the parameters applicable in CLC. The reproducibility of the analytical results obtained by CEFBC is better than in the case of TLC by a factor of 6 to 10, and approaches that known for CLC.     

Improvement of separation in zonal preparative thin-layer chromatography by gradient elution

Summary Complex extracts of the plants Azulan and Hemorigen were separated by zonal micropreparative thin-layer chromatography in sandwich chambers of the ES and DS type which permitted zonal application of large volumes of sample, without auxiliary equipment. Application from the edge of the layer, in the frontal chromatography mode, markedly improved the separation efficiency and capacity owing to displacement effects which narrow the initially broad zones. Further improvement of separation efficiency and purity of fractions, revealed by densitometry, was observed using stepwise gradient elution. This was confirmed by extraction of some of the separated fractions from the layer and rechromatography; the composition of these fractions were generally simpler than for the corresponding isocratic chromatograms.     

Design of experiment techniques for the optimization of chromatographic analysis conditions: A review

Design of experiment (DoE) techniques have been widely used in the field of chromatographic parameters optimization as a valuable tool. A systematic literature review of the available DoE techniques applied to the development of a chromatographic analysis method is presented in this paper. First, the most common available designs and the implementation steps of DoE are comprehensively introduced. Then the studies in recent 10 years for the application of DoE techniques in various chromatographic techniques are discussed, such as capillary electrophoresis, liquid chromatography, gas chromatography, thin-layer chromatography, and high-speed countercurrent chromatography. Current problems and future outlooks are finally given to provide a certain inspiration of research in the application of DoE techniques to the different chromatographic techniques field. This review contributes to a better understanding of the DoE techniques for the efficient optimization of chromatographic analysis conditions, especially for the analysis of complex systems, such as multicomponent drugs and natural products.     

Chromatographic determination of fungicides in biological and environmental matrices. New achievements

The newest results in the chromatographic analysis of synthetic and natural fungicides present in biological and environmental matrices are collected and critically evaluated. Examples of the employment of gas chromatography, liquid chromatographic technologies, such as thin-layer chromatography and high-performance liquid chromatographic methods as well as electrically driven systems are presented. The advantages and disasdvantages of the various chromatographic technologies are briefly discussed and the efficacies of the methodologies are compared.     

Processes dominating forced-flow thin-layer chromatography

Summary The effect of the vapor phase and other special influences on thin-layer chromatography have been investigated. Comparisons were made of the relationships of time vs. developing distance and flow rate vs. efficiency using a planar arrangement of the thin-layer. Covering the layer facilitates the reproducibility and of the migration front but the most effective optimization step for thin-layer chromatography is provided by forced-flow of the mobile phase. It is suggested that planar chromatography with a covered sorbent layer and using a pressurised solvent stream should be calledforced-flow thin-layer chromtatography.     

色谱在天然产物活性物质筛选中的应用

高效的活性筛选方法是新活性物质发现的关键。从筛选活性物质的角度,综述了近年来薄层色谱、高效液相色谱在天然产物活性物质筛选方面应用中的最新研究进展及其发展前景。共引用文献30篇。     

Toxicological evaluation of harmful substances by in situ enzymatic and biological detection in high-performance thin-layer chromatography

The efficiency of a chromatographic analysis method is determined by the selectivity of the chromatographic separation and the specificity of the detection method. In the case of high-performance thin-layer chromatography (HPTLC) the separated components can be detected and quantified directly on the chromatogram by physical and chemical methods. By coupling high-performance thin-layer chromatography with biological or biochemical inhibition tests it was possible to detect toxicologically active substances in situ. A linear relationship was shown between the signal of the inhibition of cholinesterase and the concentration of the inhibitor using a constant enzyme concentration and a constant incubation time. The graph of the inhibition of the luminescence of Photobacterium vibrio fisheri in relation to the concentration of pentachlorophenol (range 20–80 ng) is nearly linear. Measurements were done by using a densitometer or a videodensitometric scanner.     

Role of the solvent in thin-layer chromatography of steroids on alumina

The effects of different binary solvents on the retention behaviour of some steroids in thin-layer chromatography on alumina were studied. The slope of the linear relationship between the retention constant of the steroid and the logarithm of the volume fraction fo the polar component in the binary solvent mixture depends predominantly on the diluent. Linear relationships between the axis intercepts and slopes of particular steroids exists for all chromatographic systems examined. The slope of this relationships is a function of the retention constant of the steroid hydroxyl group.     

Influence of selected mobile phase properties on the TLC retention behavior of ziprasidone and its impurities

ABSTRACT

Influence of nine different solvents, either alone or in a mixture, on the retention behavior of ziprasidone and its five impurities were examined by normal-phase thin-layer chromatography. Migration distances of the examined compounds obtained under the examined chromatographic conditions were correlated with calculated mobile phase properties, such as Snyder polarity and Hansen solubility. Linear or second-order polynomial relationships with high correlation coefficients were established between investigated variables. The obtained mathematical functions and statistical results indicated that selected mobile phase properties can be used for the prediction of the retention behavior of ziprasidone and its five impurities.     

Determination of Selected Quinolones and Fluoroquinolones by Use of TLC

Abstract

There are many different methods of quinolones determination. The most often used method of quinolones analysis is liquid chromatography. In this work some selected quinolones (cinoxacin, pipemidic acid) and fluoroquinolones (ofloxacin, pefloxacin) were separated with thin-layer chromatography (TLC). The two different mobile phases were used as follows: buffer solution (pH = 5.5)-methanol, 40:10 (v/v) and acetonitrile-water-acetic acid, 6:40:4 (v/v/v), respectively, for quinolones and fluoroquinolones. The following chromatographic parameters were calculated for these separations: R_F, ?R_F, R_M, and R_S. The possibility of qualitative determination of cinoxacin, pipemidic acid, ofloxacin, and pefloxacin using TLC was shown.     

Binding of low molecular mass compounds to proteins studied by liquid chromatographic techniques

The newest achievements in the application of miscellaneous liquid chromatographic techniques such as size-exclusion, ion-exchange and reversed-phase high-performance liquid chromatography, and thin-layer chromatography for the elucidation of the various aspects of the binding of ligands to proteins are compiled and briefly discussed. Examples of employment in pharmaceutical and clinical chemistry, drug design, enzyme kinetic studies and environmental protection are presented.     

准圆周薄层色谱上行展开的研究

圆周薄层色谱能将样品展开为很细的谱线,具有较高的分辨能力,常用于分析一些难分离的物质。这种色谱方法过去只能采用水平展开方法。我们将普通薄层板修饰成特定形状,用最常见的上行展开法获得近似于圆周薄层的色谱。方法不需要特殊展开装置,应用于皂苷、生物碱的分离鉴定取得很好效果。     

Advances in the thin-layer chromatographic forensic analysis of inks

Advances in the use of thin layer and high-performance thin-layer chromatography for analysis of inks and ink writings in forensic investigations are reviewed. Experimental materials and techniques such as sample preparation, layers, sample application, development, detection, documentation, and interpretation of results are described and selected applications for several ink types are given. Some additional analytical techniques that complement thin-layer chromatography are also mentioned. Citations to important literature, from 2008 to 2016, are included.     

Chromatographic identification of pesticides

The chromatographic properties of 51 common pesticides have been measured using seven different chromatographic systems involving gas-liquid chromatography (GLC), high-performance liquid chromatography (HPLC) with diode-array spectrophotometric detection and thin-layer chromatography (TLC) with different spray reagents. Correlation coefficients were calculated for combinations of all systems. The best combination of the chromatographic systems examined for the identification of an unknown compound is GLC on OV-17, HPLC on ODS-Hypersil with acetonitrile-water as eluent and TLC using an isooctane-ethyl acetate solvent system.     

Planar chromatographic method development using the PRISMA optimization system and flow charts

This study presents a modern planar chromatographic method-development procedure, based on the "PRISMA" optimization system, in which the optimum separation is achieved systematically and the structures and properties of the substances to be separated are not known. The procedure consists of three stages. In the first of these the basic conditions the stationary phase, vapor phase, and individual solvents are selected with a TLC procedure (generally in nonsaturated chromatographic chambers). In the second stage, the optimum combination of the selected solvents is determined with the PRISMA model. The third part of the procedure includes the selection of the development mode (circular, linear, or anticircular); the selection of an appropriate forced-flow chromatographic technique (over-pressured layer chromatography or rotation planar chromatography) with high-performance thin-layer chromatographic plates; the transfer of the optimized mobile phase to the various analytical, planar, or column preparative liquid chromatographic techniques; and the selection of the operating conditions. For practical reasons, the optimization process is presented with the help of flow charts.     

Determination of the 7-amino-metabolites of the 7-nitro-benzodiazepines in human plasma by thin-layer chromatography

A sensitive thin-layer chromatographic method is described for the determination of the 7–amino-metabolites of flunitrazepam and clonazepam. The same procedure is applicable to other 7-nitro-benzodiazepines such as nitrazepam. A purified plasma extract of the 7-amino-metabolites is separated by thin-layer chromatography. The primary aromatic amines are diazotized and coupled with N-(1-naphthyl) ethylene-diamine on the thin-layer plate. The quantities of the 7-amino-metabolites are directly evaluated by colorimetric densitometry. The lower limit of detection is in order of 0.5–10 ng cm^?3 of plasma. The relative standard deviation of the whole procedure is less than ±15% in the range of 0.5–10 ng cm^?3 for a single determination. The unchanged drugs can be reduced on the thin-layer plate and detected by the same method. Since this procedure is rather difficult to perform, it is advantageous to determine the 7-nitro-benzodiazepines in plasma by gas chromatography. The thin-layer chromatographic method was used to measure the 7-amino-metabolites in plasma of patients on either a flunitrazepam or a clonazepam oral dosing regimen.     

Behavior of peptides and computer-assisted optimization of peptides separations in a normal-phase thin-layer chromatography system with and without the addition of ionic liquid in the eluent

The addition of an ionic liquid into the mobile phase appeared to be useful in optimization of chromatographic separation of peptides. Different behavior of peptides in thin-layer chromatography (TLC) was observed after addition of 1-ethyl-3-methylimidazolium tetra fluoroborate to the eluent in comparison to the system without the ionic liquid. Nonlinear dependence of the retention coefficient, R(M), of peptides on the volume percentage of acetonitrile in the eluent was found in normal-phase TLC with and without immidazolium tetra fluoroborate in the mobile phase. In general, R(M) increased with increasing concentration of acetonitrile. In TLC systems without the ionic liquid, R(M) can be described well with a quadratic function. On the other hand, in a TLC system with an ionic liquid as the additive to the mobile phase, the retention behavior is better described with a third-degree polynomial function. The potential usefulness of ionic liquids for optimization of separation of peptides was demonstrated. Optimization of the separation conditions was supported by a commercially available computer program.