Thin-layer chromatography TLC silica

Fig. 2 The 1-D (A) and 2-D (B) chromatograms of the mixture of the seven bile acids investigated on thin-layer chromatography (TLC) silica gel 60 (E. Merck, 1.05553). I. Eluent n-hexane-ethyl acetate-acetic acid (25 20 5, v/v). II. Eluent chloroform-n-butanol-acetic acid-water (2 32 2 2, v/v) M represents bile acids mixture where 1 indicates chenodeoxycholic acid, 2 glyco-deoxycholic acid, 3 deoxycholic acid, 4 lithocholic acid, 5 cholic acid, 6 glycocholic acid, and 7 glycolithochoUc acid.

Thin-layer chromatography (TLC) Silica, cellulose Liquid Flat Adsorption or partition... 

Thin-layer chromatography (TLC) Silica, cellulose, ion-exchange resin, controlled porosity solid Liquid Planar Adsorption (partition, ion-exchange, exclusion)... 

An important publication by Kost et al. (63JGU525) on thin-layer chromatography (TLC) of pyrazoles contains a large collection of Rf values for 1 1 mixtures of petroleum ether-chloroform or benzene-chloroform as eluents and alumina as stationary phase. 1,3- and 1,5-disubstituted pyrazoles can be separated and identified by TLC (Rf l,3>i y 1,5). For another publication by the same authors on the chromatographic separation of the aminopyrazoles, see (63JGU2519). A-Unsubstituted pyrazoles move with difficulty and it is necessary to add acetone or methanol to the eluent mixture. Other convenient conditions for AH pyrazoles utilize silica gel and ethyl acetate saturated with water (a pentacyanoamine ferroate ammonium disodium salt solution can be used to visualize the pyrazoles). 

These can usually be easily separated by thin layer chromatography (TLC) on silica gel. 

Analysis by thin layer chromatography (TLC) indicates product formation and a small amount of starting material. TLC was performed on Merck Silica gel 60 F-254 coated on aluminum sheets. Product 3 has Rf = 0.44 (elution with 70 30 petroleum ether-ethyl acetate visualization with iodine vapor). 

Paper chromatography (PC) and thin layer chromatography (TLC) have been used since the 1940s. Preparative PC on Whatman 3 paper, analytical PC on Whatman 1 paper, and analytical TLC on microcrystalline cellulose, silica gel, or polyamide have been applied with a variety of solvents and the behaviors of anthocyanins have been similar in all media. Two-dimensional TLC allows the separation of several compounds and has been nsed to clarify the anthocyanin compositions of different commodities. ... 

Tswett s initial column liquid chromatography method was developed, tested, and applied in two parallel modes, liquid-solid adsorption and liquid-liquid partition. Adsorption ehromatography, based on a purely physical principle of adsorption, eonsiderably outperformed its partition counterpart with mechanically coated stationary phases to become the most important liquid chromatographic method. This remains true today in thin-layer chromatography (TLC), for which silica gel is by far the major stationary phase. In column chromatography, however, reversed-phase liquid ehromatography using chemically bonded stationary phases is the most popular method. 

The components in the organic phase were separated first using thin-layer chromatography (TLC). The organic phase (80 ml) was streaked onto 20 plates of 1000 ym silica GF (Analtech, Inc.,... 

Although the interest in, and application of layer chromatography has historically resulted from the development of PC, it was soon replaced by thin-layer chromatography (TLC). In PC, only one stationary phase matrix is available (cellulose), at variance to TLC (silica, polyamide, ion-exchange resins, cellulose). Using a silica-gel plate, separation of a sample can be accomplished in approximately 1 h as compared with many hours on paper. The plate size is much smaller than the necessary paper size. Also, more samples can be spotted... 

Examine by thin-layer chromatography (TLC) using a suitable TLC silica gel as the coating substance on the TLC plate. The method requires preparation of the following solutions ... 

Analytical thin layer chromatography (TLC) was conducted on 10 x 2.5-cm precoated glass plates (silica gel GF, 0.25-mm thickness, Analtech), eluted with 10% ethyl acetate in hexane, and visualized with both UV (254 nm) and aqueous 50% sulfuric add spray/heating. The carbene complex moves as an orange spot on TLC the reaction is complete when this spot is no longer visible. 

The difference between this technique and GC or HPLC is that the separation process occurs on a flat essentially two-dimensional surface. The separated components are not usually eluted from the surface but are examined in situ. Alternatively, they can be removed mechanically for further analysis. In thin-layer chromatography (TLC), the stationary phase is usually a polar solid such as silica gel or alumina which is coated onto a sheet of glass, plastic, or aluminium. Although some moisture is retained by the stationary phase, the separation process is predominantly one of surface adsorption. Thin layers are sometimes made from ion-exchange or gelpermeation materials. In these cases the sorption process would be ion-exchange or exclusion. 

Most of the reactions described in the following chapters were monitored by Thin Layer Chromatography (TLC) using plastic TLC plates coated with a thin layer of Merck 60 F254 silica gel. The products were detected by using an ultraviolet lamp or the TLC plates were treated with p-anisaldehyde reagent, prepared as explained below, and then heated to 120 °C to stain the spots. After visualization and measurement, the Rf values were recorded. 

Methylacrylate and ethylenediamine were obtained from the Merck. Jeffamine T-3000 was purchased from Texaco Chemical Company. Other chemicals were used as obtained from the Fluka without further purification unless otherwise noted. Solvents were dried and distilled according to literature procedures prior to use. Reactions were controlled by thin layer chromatography (TLC) on silica gel 60 F254 and spots were detected either by UV-visible light or by charging with vapor. 

Thin Layer Chromatography (TLC). Commercially available (Whatman LK6D, linear-K) silica gel (40S) plates of 250 ym thickness were used. These were developed in chloroform acetone formic acid (80 19 1). Spots were detected by UV light and iodine vapor. 

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