The Mobile Phase Motion in Ascending Micellar Thin-Layer Chromatography with Normal-Phase Plates

JPC – Journal of Planar Chromatography – Modern TLC - The physical-chemical characteristics (surface tension and viscosity) of micellar mobile phases based on the cationic surfactant...     

Recycled X-Ray Films as an Alternative Support for Thin-Layer Chromatography Plates

JPC – Journal of Planar Chromatography – Modern TLC -     

Reversed-Phase Stepwise Gradient Thin-Layer Chromatography of 19 Test Dye Mixtures with a Single Void Volume of the Mobile Phase

JPC – Journal of Planar Chromatography – Modern TLC - Satisfactory separation of a test mixture of 19 dyes with a general elution problem was obtained by reversed-phase stepwise...     

Circular-Development with Overpressured Thin-Layer Chromatography

Abstract

A novel type modification of circular thin-layer chromatography has been developed, in which the layer is tightly covered by a membrane, eliminating the vapour phase over the sorbent layer. The developing solvent is pumped through the apparatus.     

分子印迹薄层色谱手性固定相的制备及其色谱性能

分别以右旋扁桃酸、右旋邻氯扁桃酸和右旋对氯扁桃酸为模板,丙烯酰胺、乙二醇二甲基丙烯酸酯为功能单体和交联剂合成分子印迹聚合物,并以此作为薄层色谱手性固定相。研究了模板分子消旋体在手性固定相上的分离情况,并讨论了展开剂中乙酸含量对分离的影响。在乙腈-5%乙酸展开体系中扁桃酸、邻氯扁桃酸和对氯扁桃酸消旋体得到较好的分离,分离因子分别为1.45,1.62和1.56。该手性固定相对模板分子的结构类似物也具有一定的手性交叉分离能力。讨论了分析物的化学结构对该手性固定相识别性能的影响。该方法为快速、灵敏地对手性物质分析、定性提供了一条简便的途径。     

Thin-Layer Chromatography of Anions — Separation of Coexisting Hexacyanoferrate(II), Hexacyanoferrate(III) and Thiocyanate with a New Mobile Phase

JPC – Journal of Planar Chromatography – Modern TLC - The thin-layer chromatography of eighteen anions has been performed on silica layers with mixed aqueous–organic mobile...     

A New Anionic Micellar Mobile Phase System for the Normal-Phase Thin-Layer Chromatography of Amino Compounds: Simultaneous Separation of Aminophenol Isomers

The chromatography of some amino compounds was performed on high-performance thin-layer plates (silica-gel 60 F₂₅₄, catalog no. 1.05554, Merck, Germany) using aqueous and alcoholic (MeOH) and aqueous–organic solutions of cationic, anionic, and nonionic surfactants. The results obtained with 0.01 M aqueous sodium dodecyl sulfate (SDS) have been compared with distilled water (i.e., zero SDS) as the eluent. The effects of the surfactant concentration, the nature of the alcohol, and the presence of inorganic salts (NaCl, LiCl, CaCl₂, and CoCl₂) in the mobile phase were examined in order to understand the mobility pattern of amino compounds. Among the added salts, CaCl₂ was found to be the most effective for facilitating an analytically important separation of coexisting ortho-, meta-, and para-aminophenols. The TLC system consisting of a precoated high-performance silica layer as the stationary phase and 0.01 M methanolic SDS plus 0.1 M CaCl₂ in a 3 : 7 ratio as the mobile phase was identified as the most suitable system for the separation of o-, m-, and p-APHS from their mixtures. The influence of various impurities, such as amines, phenols, and inorganic cations, on the mobility and the separation of coexisting aminophenol isomers has also been examined. The lower limits of detection of aminophenols were determined on HPTLC plates using I₂ vapors as the detection reagent.     

Study of the Absorption Characteristics of a Zeolite Support in Normal and Reversed-Phase Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - The retention behavior of 36 synthetic dyes has been studied in adsorption and reversed-phase TLC on zeolite layers with n-hexane,...     

Effect of Mobile Phase pH* on Chromatographic Behaviour in Chiral Ligand-Exchange Thin-Layer Chromatography (CLETLC) of Amino Acid Enantiomers

The enantiomers of some amino acids have been separated on commercial chiral TLC plates in reversed-phase mode. The effect of the pH* of the aqueous-organic mobile phase on the retention and mobility of the enantiomers and on selectivity was investigated. It was shown that for most of the amino acids investigated the highest enantioselectivity was obtained at pH* 3–4 or 6–7. The drift and disturbance of the baseline on the chromatograms were also much smaller at pH* 3–4 and 6–7.     

手性配位体交换流动相添加剂法拆分对映体

综述了手性配合基交换色谱法通常采用三种手性相系统中的流动相添加剂方法。主要内容有：（Ａ）手性配合基交换机制,给出了描述对映体对在色谱系统中的保留时间和分离选择性的公式,包括手性选择剂在固定相和流动相中的各种不同情况。公式表明整个色谱往系统的对映体选择性不同于溶液中所存在的选择剂与被选择物作用的情况;（Ｂ）影响配合交换的参数,讨论了金属离子、金属离子／配位体比率、金属离子络合物浓度、固定相、流动相ｐＨ、洗脱顺序、有机调节剂、离子对试剂、流动相离子强度、温度、立体选择性和手性交互识别;（Ｃ）应用。     

Assessment of Mobile Phase Flow Resistance of Fused Microplatelet Alumina-Based Stationary Phases for Reversed Phase High Performance Liquid Chromatography

Abstract

The mobile phase flow resistances (φ's) of several stationary phases consisting of surface-modified Unisphere^TM fused microplatelet alumina particles were determined and compared with corresponding values obtained from stationary phases based upon more conventional spherical and angular silica and alumina particles. Although the φ value obtained for a fused-microplatelet alumina-based phase was slightly lower than the value obtained on a spherical alumina-based phase with similar particle dimensions and surface modification, factors other than particle shape were found to have a substantial effect on mobile phase flow resistance. Larger φ values were obtained with phases with smaller average particle diameters. These were attributed to the presence of greater numbers of microparticles with diameters less than 5 microns in such phases. Larger φ values obtained for wide pore (21 nm) and octyl-bonded alumina-based phases over narrow pore (11 nm) and octadecyl-bonded phases were attributed to the former's ablities to entrap larger volumes of stagnant mobile phase within their pores.     

Normal- and Reversed-Phase Thin-Layer Chromatography of Amino Acids on Unconventional Supports with Mixed Mobile Phases Containing Dimethyl Sulfoxide

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of twenty-four amino acids has been studied on untreated and on triaryl phosphate (TAP)-impregnated...     

Overpressured Thin-Layer Chromatography and Its Applications

Abstract

In recent years, a rapid progress can be observed both in column and planar liquid chromatographic techniques. In the field of liquid column chromatography the most spectaular achievement was the development of high-performance liquid chromatographic/HPLC/ systems by means of several special instruments and sorbents/1, 2/. As regards planar techniques, the most significant break-through is the development of highperformance thin-layer chromatography/HPTLC//3/ based on the application of fine-particle sorbents. Both techniques proved to be very useful in many fields of chemical analysis, although the use of the latter is more restricted, mainly to micro chromatographic studies.     

Some Technical Problems Associated with Temperature-Controlled Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC -     

Densitometric High-Performance Thin-Layer Chromatography Method for Toxigenity Testing of Alternaria alternata Strains Isolated from Foodstuffs

JPC – Journal of Planar Chromatography – Modern TLC - Alternaria alternata is an important mycotoxin-producing species that occurs on cereals, sunflower seeds, oilseed rape, tomato,...     

Micellar Thin-Layer Chromatography and Preconcentration of L-Carnitine with Magnetite Nanoparticles

Journal of Analytical Chemistry - Thin-layer chromatography (TLC) is used to study the chromatographic behavior of L-carnitine in aqueous–organic mobile phases (MPs) and aqueous MPs in the...     

Reversed Phase High Performance Liquid Chromatography Using Carboxylic Acids in the Mobile Phase

Abstract

This report describes the use of different carboxylic acids as mobile phase modifiers. The effect on retention of acid chain length, pH, and eluent composition for a series of phenylalkanols, phenol, and the amines aniline, N-methylaniline, and benzylamine is discussed. The retention of both neutral and positively charged compounds is influenced by the dissociation equilibrium of the carboxylic acid in the mobile phase. By using l-pentanol to coat excess exposed silanol groups on the reversed phase column used, the inflection in the retention of both neutral and charged solutes as pH is changed occurs at the pK_a of the acid in the mobile phase. In addition, by using an acid and amine with the same or similar pK_a values, selective ion-pairing of this pair over others with dissimilar pK_a values can be promoted. Application of this technique to the selective retention of amino acids and peptides was unsuccessful.     

正相薄层色谱中常见人参皂甙结构与保留值之间关系的初步研究(英文)

 在硅胶薄层板上用氯仿-乙酸乙酯-甲醇-水(体积比为15∶40∶22∶10)作展开剂,测定了常见人参皂甙的Rf值。为了研究它们的结构与保留值之间的关系,对它们的17种结构参数进行了计算。除了拓扑指数和理化参数外,引入了代表构成人参皂甙的母体化合物种类并反映它们分子极性特征的新参数“E”。通过相关分析优化选出范德华分子表面积AW、拓扑指数0B和参数E,建立了多参数线性回归方程,较好地描述了在正相薄层色谱中常见人参皂甙结构与保留值之间的关系,并与人工神经网络方法进行了比较。     

Analysis of PCB's by Thin-Layer Chromatography

Abstract

A screening thin layer chromatography (TLC) technique has been developed that can be done in the field. Quantitative analysis by TLC densitometry can be done in a laboratory (or field van). A densitometer is needed for quantitative work by TLC. An Apple computer may be added to use as a computational device. Semi-quantitative results may be obtained by visual comparisons. Confirmations may be made by silver halide visualization on TLC. Dehalogenation with sodium biphenyl, chlorination with antimony pentachloride, or mass spectral confirmation may be used. Quantitative analysis is possible of the derivatized positive samples.