Reversed Phase Thin-Layer Chromatography

Another cultured cell line of Catharanthus roseus (EU4A), which does not produce detectable amounts of vinblastine and other bisindole alkaloids, was also examined for its ability to transform 78 (183). Cell-free extracts of the culture line were prepared, and the 35,000 X g supernatant solution was used. Incubations with 2r-tritioanhydiovinblastine yielded a mixture from which radioactive vinblastine (52) was isolated. The labeled vinblastine was reisolated after unlabeled carrier was added and rigorously purified by successive thin-layer chromatography, reversed-phase HPLC, and crystallization to constant specific activity. Boiled extracts could not produce labeled 52, thus supporting the involvement of enzymes in the conversion process. 

Ion pair chromatography represents a valuable variant in thin layer chromatography. Reversed-phase layers are particular suitable as these layers have no or only a few adsorptive properties. Chromatography is possible with simple systems, e.g. mixtures of methanol or acetonitrile with water. In contrast to HPLC it is possible to use mobile phases with pH > 8. 

Ni et al. [144] also investigated the profiles of major metabolites of primaquine produced from liver microsomal and mitochondrial metabolism, in vitro by silica gel thin-layer and reversed-phase high performance liquid chromatography. The results... 

Thin-layer chromatography (TLC) is probably one of the most frequently used and by far the simplest chromatographic techniques used to separate or purify compound mixtures. Commercially available TLC plates that are used in laboratories allow resolution of compounds on many types of stationary phases such as thin-layer silica, reversed phase (RP) modified silica, cellulose, or aluminum oxide. TLC technique is widely used because it has many important advantages such as low cost, low solvent consumption, simultaneous elution of many different samples on one TLC plate, and no memory effects [1-2]. 

Chemical stabiUty studies are monitored by siUca gel thin-layer chromatography (dc) or by high performance Hquid chromatography (hplc) using a reverse-phase C g coated column (24). Hplc peaks or dc spots are visualized by thek uv absorption at 245 nm the tic spots can also be detected by ceric sulfate or phosphomolybdic acid staining. 

The lipophilicity (7 m value) and specific hydrophobic surface area of 1 ]/f-pyrido[2,]-fi]quinazolin-] 1-one and its isomeric 6//-pyrido[l, 2-u]qui-nazolin-6-one were determined by reversed-phase thin-layer chromatography (98MI4). 

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. 

Not only in HPLC, but also in modem thin-layer chromatography, the application of reversed-phase stationary phases becomes increasingly important. The advantage of the hydrophobic layers in comparison with the polar, surface-active stationary phases is the additional selectivity and a reduced hkehhood of decomposition of sensitive substances. 

In reversed-phase thin-layer chromatography (RP-TLC), the choice of solvents for the mobile phase is carried out in a reversed order of strength, comparing with the classical TLC, which determines a reversed order of values of compounds. The reversed order of separation assumes that water is the main component of the mobile phase. Aqueous mixmres of some organic solvents (diethyl ether, methanol, acetone, acetonitrile, dioxane, i-propanol, etc.) are used with good results. 

Lipophilicity represents the affinity of a molecule or a moiety for a lipophilic environment. It is commonly measured by its distribution behavior in a biphasic system, either liquid-liquid (e.g. partition coefficient in 1-octanol-water) or solid-liquid (retention on reversed-phase high-performance liquid chromatography or thin-layer chromatography system). 

Lipophilicity and specific hydrophobic surface area were determined by using reversed-phase thin-layer chromatography for fused heterocyclic ring systems including five pyrido[2,iy][l,2,4]triazine derivatives <1998MI64>. 

The logarithm of the 1 -octanol - water partition coefficient, denoted log Kq j or log P, indicates the distribution of the compound between the organic and the water phase. For highly lipophilic compounds, the log P is determined via reversed-phase thin-layer chromatography, giving the so-called log P tlc value1. 

Reversed-phase thin-layer chromatography (TEC) (Ellgehausen et al. 1981, Bruggeman et al. 1982). 

Bruggeman, W. A., van der Steen, J., Hutzinger, O. (1982) Reversed-phase thin-layer chromatography of polynuclear aromatic hydrocarbons and chlorinated biphenyls. Relationship with hydrophobicity as measured by aqueous solubility and octanol-water partition coefficient. J. Chromatogr. 238, 335-346. 

T. Cserhati, E. Forgacs and J. Hollo, Separation of color pigments of Capsicum annuum by adsorption and reversed phase thin layer chromatography. J. Planar Chromatogr.—Mod. TLC 6 (1993) 472 175. 

R.T. Evans, B. Fried and J. Sherma, Effects of diet and larval trematode parasitism on lutein and / -carotene concentrations in planorbid snails as determined by quantitative high performance reversed phase thin layer chromatography. Comp. Biochem. Physiol. PartB 137 (2004) 179-186. 

D.M. Milojkovic-Opsenica, K. Lazarevic, V. Ivackovic and Z.Lj. Tesic, Reversed-phase thin-layer chromatography of some foodstuff dyes. J. Planar Chromatogr.-Mod TLC, 16 (2003) 276-279. 

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