Thin-layer chromatography, comparison

Mercadante A.Z. and Rodriguez-Amaya, D.B., Screening of carotenoids comparison of thin-layer chromatography with high-efficiency thin-layer chromatography, with multiple development, Cienc. Tecnol. Alim., 11, 200, 1991. 

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. 

Clark et al. [53] subjected primaquine to metabolic studies using microorganisms. A total of 77 microorganisms were evaluated for their ability to metabolize primaquine, of these, 23 were found to convert primaquine to one or more metabolites (thin-layer chromatography analysis). Preparative scale fermentation of primaquine with four different microorganisms resulted in the isolation of two metabolites, identified as 8-(3-carboxy-l-methylpropylamino)-6-methoxyquinoline and 8-(4-acetamido-l-methylbutylamino)-6-methoxyquinoline. The structures of the metabolites were proposed, based primarily on a comparison of the 13C NMR spectra of the acetamido metabolite and the methyl ester of the carboxy metabolite with that of primaquine. The structures of both metabolites were confirmed by direct comparison with authentic samples. 

This is considered to be largely a qualitative technique. Difficulties that arise in obtaining reproducible quantitative data are similar to those encountered in thin-layer chromatography. In addition, adsorption characteristics of dyes on macromolecules are so variable that only semiquantitative comparisons can be made. These are, however, still very useful... 

J. Sherma, Comparison of thin layer chromatography with liquid chromatography, J. Assoc. Off. Anal. Chem., 74 (1991) 435-437. 

Injection volumes of 5pl were used for both sample solutions and comparison standards. Qualitative residue confirmation was accomplished with thin layer chromatography using silica gel. Plates were developed with 1% chloroform in n-heptane, and visualized with alkaline silver nitrate spray as the chromogenic agent. Alternatively, p,p5-DDT and p,p5-TDE were confirmed by treatment with 5% methanoic potassium hydroxide [40]. Partial confirmation of Dieldrin was achieved by fractionating the analysis solution on a Mills column, thus isolating Dieldrin in the second fraction [35],... 

AHLs can be tentatively identified by comparison of the unknown with synthetic AHL standards after Thin Layer Chromatography (TLC) in which the plates are overlaid with agar containing one of the AHL biosensors described above [37,39,44,45]. However, for the unequivocal identification of AHLs the use of more powerful methods such as LC-mass spectrometry, nuclear magnetic resonance and infrared spectroscopy as described below are required. 

Novatchev, N., and Holzgrabe, U. (2002). Comparison of the suitability of capillary electrophoresis and thin-layer chromatography for determination of impurities In amino acids. Pharmeuropa 14(4), 640-647. 

The two potato glycoalkaloids in the potato extract were identified as follows (a) comparison of thin-layer chromatography of standards a-chaconine and a-solanine and of samples of each peak collected from the HPLC column containing the individual glycoalkaloids and (b) HCl hydrolysis of the HPLC samples into sugars and the aglycon solanidine. These were identified by GLC-MS (Kozukue et al., 1999, 2008 Kozukue and Friedman, 2003). 

The dioxepin ring was then formed by dehydration of the secondary alcohol 127 with MTPI in DMPU to afford 14-oxo-PHB 12 [7]. This material has been previously described by a Pharmacia group (obtained semi-synthetically from MFA) and comparison of the authentic and synthetic materials [ H and 13C NMR, IR, exact mass, mobility on thin-layer chromatography (TLC)] conformed the identity of this substance. Treatment of the synthetic ketone with MeMgBr gave (-)-PHA (2) in 42% yield that was identical in all respects [ H and 13C NMR, IR, exact mass,... 

Column and thin-layer chromatography (TLC) came into use at about the same time as GLC, with the latter widely accepted because of its speed, ease of use, versatility, resolving power, and, probably most important, ease of visualization. Thin-layer chromatography has been particularly useful in the separation and nondestructive recovery of lipid classes. Tentative identifications can be made by comparison with known compounds, and purity can be checked. Jensen et al. (1961) may well have been the first group to separate milk lipid classes with TLC when they used the technique to obtain diacylglycerols from lipo-lyzed milk lipids. 

Kiffe, M., Jehle, A., and Ruembeli, R. (2003). Combination of high-performance liquid chromatography and microplate scintillation counting for crop and animal metabolism studies A comparison with classical on-line and thin-layer chromatography radioactivity detection. Anal. Chem. 75 723-730. 

BHC isomers Light petroleum Comparison of GLC and thin-layer chromatography [296]... 

A solution containing 5.0 mg of N-trifluoroacetyladriamycin dissolved in 0.5 ml of anhydrous pyridine was treated with 18 microliters of valeryl chloride, which was added in small portions over a two-day period. The reaction was monitored by thin layer chromatography and when the presence of N-trifluoroacetyladriamycin could no longer be observed, the reaction mixture was diluted with 10 ml of chloroform. The chloroform solution was extracted three times with pH 4 buffer and once with pH 7 buffer. The dried chloroform solution was then evaporated under reduced pressure, and the residue was purified by preparative thin layer chromatography on silica gel G with chloroform methanol water (120 20 1 by volume) as the solvent system. The major orange-colored band was removed and washed free of silica gel with a mixture of methanol and ethyl acetate. Upon evaporation of the methanol and ethyl acetate, 2.19 mg of N-trifluoroacetyladriamycin-14-valerate was obtained. This material was idential by spectral and chromatographic comparison with samples of N-trifluoroacetyladriamycin-14-valerate prepared by earlier described methods. 

C. A. T. Brinkman and G. de Vries, Thin-layer chromatography on chemically bonded phases a comparison of precoated plates, J. Chromatogr., 258 43 (1983). 

Table 14.2 Comparison between algal pigment analyses carried out by the high performance liquid chromatographic method, by reflectometric thin layer chromatography, and by the polychromatic method...

The methyl esters of fatty acids can be separated by thin-layer chromatography (TLC). They can be identified by comparison of their rate of migration (Rf values) to the Rf values of authentic samples of methyl esters of different fatty acids (Fig. 41.1). 

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