Mobile phase in thin-layer chromatography

Gocan, S., Mobile phase in thin-layer chromatography, in Modern Thin-Layer Chromatography, Grinberg, N., Ed., Chromatographic Science Series, 52, Marcel Dekker, New York, 1990, chap. 3. 

Source From The mobile phase in thin-layer chromatography, in Modem Thin-Layer Chromatography - ... 

Hara, S., and Mibe, K. (1975). Systematic analysis of steroids. Solvent selectivity of the mobile phase in thin-layer chromatography in relation to the mobility and the structure of steroidal pharmaceuticals. Chem. Pharm. Bull. 23 2850-2859. 

Gocan, S. The Mobile Phase in Thin-Layer Chromatography. In Modem Thin-Layer Chromatography Grinberg, N., Ed. Marcel Dekker New York, 1990 139. Chap. 3. Kovalsca, T. Klama, B. JPG, J. Planar Chromatogr. 1997, 10, 353-357. 

Because of the similarities in the theory and practice of these two procedures, they will be considered together. Both are examples of partition chromatography. In paper chromatography, the cellulose support is extensively hydrated, so distribution of the solutes occurs between the immobilized water (stationary phase) and the mobile developing solvent. The initial stationary liquid phase in thin-layer chromatography (TLC) is the solvent used to prepare the thin layer of adsorbent. However, as developing solvent molecules move through the stationary phase, polar solvent molecules may bind to the immobilized support and become the stationary phase. 

Mobile phase for thin-layer chromatography—Mix 1.5 liters of chloroform, 600 ml of t-amyl alcohol, and 60 ml of glacial acetic acid. Store tightly covered in a dark bottle at room temperature. 

Golkiewicz, W. and Polak, B., Relationship between capacity factors and composition of a mobile phase in thin-layer liquid exchange chromatography of enantiomers of some amino acids, J. Planar Chromatogr., 7, 453, 1994. 

Immobilization. The abiUty of cyclodextrins to form inclusion complexes selectively with a wide variety of guest molecules or ions is well known (1,2) (see INCLUSION COMPOUNDS). Cyclodextrins immobilized on appropriate supports are used in high performance Hquid chromatography (hplc) to separate optical isomers. Immobilization of cyclodextrin on a soHd support offers several advantages over use as a mobile-phase modifier. For example, as a mobile-phase additive, P-cyclodextrin has a relatively low solubiUty. The cost of y- or a-cyclodextrin is high. Furthermore, when employed in thin-layer chromatography (tic) and hplc, cyclodextrin mobile phases usually produce relatively poor efficiencies. 

Retention in RPC with 34-60% (v/v) methanol-water as the mobile phase has been shown to correlate well to log P by Riley et-aL (192) at each mobile phase composition. A mild dissent has been made by investigators (289) who found a correlation between RPC retention and log P but who claimed a closer relationship between the corresponding data obtained in thin-layer chromatography in the system oleyl alcohol-water and log P (289). 

By appropriate choice of the type (or combination) of the organic solvent(s), selective polar dipole-dipole, proton-donor, or proton-acceptor interactions can be either enhanced or suppressed and the selectivity of separation adjusted [42]. Over a limited concentration range of methanol-water and acetonitrile-water mobile phases useful for gradient elution, semiempirical retention equation (Equation 5.7), originally introduced in thin-layer chromatography by Soczewinski and Wachtmeister [43], is used most frequently as the basis for calculations of gradient-elution data [4-11,29,30] ... 

Sz. Nyiredi, C.A.J. Erdelmeier, B. Meier, O. Sticher, The PRISMA mobile phase optimization in thin-layer chromatography Separation of natural compounds, Planta Medica 3 (1985) 241-246. 

The most commonly used approach in thin-layer chromatography (tic) entails separations on a silica gel plate where tire silica gel is coated as a thin layer on a glass plate. The plate is developed using the mobile phase... 

The approach of CMPAs has also been used in thin-layer chromatography (TLC) for the chiral resolution of a variety of racemic compounds [100-110]. Lepri et al. [104,105] used BSA as a mobile phase additive for the chiral resolution of dansyl amino acids and other drugs by TLC. Armstrong et al. [101,102] used unde-rivatized and hydroxyethyl and hydroxypropyl /I-cyclodextrins for the chiral resolution of dansyl amino acids, alkaloids, and other compounds. Aboul-Enein... 

Modification of the Activity of Alumina by Addition of Water Stationary and Mobile Phases Typical Stationary and Mobile Phase Systems Used in the Separation of Various Inorganic Ions Spray Reagents in Thin-Layer Chromatography Protocol for Reagent Preparation... 

In Thin-Layer Chromatography (TLC), the a-cyclodextrin (12-14) and the soluble 6-cyclodextrin polymers have been thoroughly studied as components of the mobile phase. The y-cyclodextrin, because of its excellent solubility, is also promising, especially for larger molecules, but has not yet been studied. Several attempts have demonstrated that TLC-plates coated by insoluble finely powdered cyclodextrin-polymers (i.e. cyclodextrin in stationary phase) can separate isomers, but this possibility has not yet been fully exploited. 

CD s dissolved in the mobile phase solutions have been used in thin-layer chromatography with polyamide stationary phase (29,30) and 2) CD complexation equilibria of ionic compounds were studied by a chromatographic method using an ion exchanger as stationary phase and mobile phase solutions containing CD s in various concentrations (31). 

Background and principles Thin-layer chromatography is the other most commonly used form of planar chromatography and uses a very similar experimental approach to paper chromatography. The principal difference is that this technique relies on the separation of biomolecules from a mixture on the basis of partition and/or adsorption. There is a distinct difference between the process of adsorption and a/isorption, and they are not interchangeable terms Whereas molecules that are a/isorbed are taken up into , those that are adsorbed stick to a surface. So, in thin-layer chromatography, the mobile phase is adsorbed (sticks to) and subsequently moves along the stationary phase. The stationary phase consists of an adsorbent (sticky) layer on a flat plate or sheet. The most commonly encountered adsorbent layers comprise silica gel, alumina (not aluminium) or cellulose, while popular solvents include hexane, acetone and alcohol. 

The progress in thin-layer chromatography was made possible by improvements in the stationary phases, optimisation of mobile phase composition, and in chromatographic instrumentation. 

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