The uses of thin-layer chromatography

TLC has been used in the study of many homopolymers polystyrene, poly(methyl methacrylate), poly(ethylene oxide), polyisoprene, poly(vinyl acetate), poly(vinyl chloride) and polybutadiene. Their molecular weight, molecular-weight distributions, microstructure (stereo-regularity, isomerism and the content of polar end groups), isotope composition and branching have been studied. For copolymer characterisation (e.g. purity and compositional inhomogeneity), random copolymers such as styrene-methacrylate, and block copolymers such as styrene-butadiene, styrene-methyl methacrylate and styrene-ethylene oxide have been separated. A good review article on polymers 

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Thin-Layer Chromatography. A study using thin-layer chromatography both for separating components of a pyrethrum extract and for purifying single components has been made. Other reports have mentioned the use of thin-layer chromatography in various connections related to pyrethrin analysis. Stahl (14) reported on pyre-thrins I and II and evidence for presence of other compounds from... 

On the thermal cyclization of compound (806) in boiling Dowtherm A for 30 min, only the linear product (813) was obtained in 59% and 67% yields (75GEP2416519 77MI4). In these cases, however, the product was not investigated by the use of thin-layer chromatography (TLC) or NMR. 

The identification and quantitation of the individual amino acids in a mixture is often required in metabolic studies and investigations of protein structure. The use of thin-layer chromatography or electrophoresis may be adequate to indicate the relative amounts and number of different amino acids in a sample but the use of gas-liquid chromatography or an amino acid analyser is essential for quantitative analysis. 

Majer, J. R., R. Perry, and J. M. Reade. The use of thin-layer chromatography and mass spectrometry for the rapid estimation of trace quantities of air pollutants. J. Chromatogr. 48 328-333, 1970. 

The use of thin-layer chromatography for the determination of sugars in honey has been proposed,77 and the potential value of gas-... 

An analagous process for isolating and concentrating portions of a sample is the use of thin layer chromatography. Here, however, it is common practice, in the treatment of an unknown sample, to place a known standard on the same plate and to run the two systems parallel so that differences in performance of an adsorbing system from one laboratory to another are accounted for by basing isolation of the desired components from the plate on the determined position of the known standard, run on the same plate. The normally limited capacity of thin layer chromatographic systems tends to exclude their wide use for the combined isolation-concentration steps of trace analysis, but circumstances in which this technique may be useful should not be overlooked. ... 

One milligram of microsomal protein is added to 0.1 M potassium phosphate buffer (pH 7.4) containing 50 mM NaF, 10 mM dithiothreitol, 1 mM EDTA, 20% glycerol (v/v), 150 iM 5-cholestene-3/3, 7a-diol, and 0.915% CHAPS. The reaction is initiated by 1 mM NAD+ to give a final reaction volume of 1.0 mL. After incubation at 37°C for 5 minutes, the reaction is terminated by adding 2 mL of 95% ethanol. An internal recovery standard, 4-cholesten-3-one (3 fig in methanol) is also added. The steroid products are extracted into 5 mL of petroleum ether (repeated twice). After the ether has been removed at 40°C under a stream of nitrogen, the products are dissolved in 100 fxL of mobile phase and 20 ju.L is injected into the column. The amount of product formed is linear with protein (to 1.5 mg) and with time (up to 10 min, 1 mg protein). The assay is much more sensitive than the direct spectrophotometric assay, and it avoids the use of thin-layer chromatography and radioisotopes described in other methods. 

Following the possible identification of the presence of LSD, the next stage in the analysis is the use of thin layer chromatography (TLC). This is employed because although it cannot be used to prove the identity of LSD, it can be used as a rapid, cost-effective method to eliminate those samples which gave a positive colour reaction in the presumptive tests but which do not contain this drug. These will be rarer when blotter acids are suspected, but may be more common where other substrates have been used as the carrier medium for the LSD itself. 

In the 1950s and 1960s a major impetus was given to the use of thin-layer chromatography by Stahl [ 15-17) who constructed a spreader for the preparation of thin-layer plates, suggested the silica adsorbent ( silica gel nach Stahl ), and edited excellent text books, etc. Simultaneously, equipment for developments, chemicals, and laboratory supply for TLC became commercially available. 

Immediately after obtaining his doctorate in chemistry in 1960, Dr. Fred Volk joined the ICT, which had then just been built in Pfinztal, where he worked closely with Dr. Karl Meyer. The main focus of his research within the area of explosive analysis was on the use of thin-layer chromatography and mass spectrometry as well as on calculating thermodynamic energies used in explosive and combustion processes. The many key words and the related articles in Explosives dealing with theoretical and thermodynamic performances were painstakingly checked, or written by Dr. F. Volk himself, each time before a new edition was printed. 

There are three convenient ways in which P can be determined in the chemistry laboratory. These are the original shake flask method, the use of thin-layer chromatography or the use of reversed-phase, high-performance liquid chromatography. 

An old method that has been revived is the use of thin layer chromatography plates for the detection of sesquiterpenoids [104,105]. While this kind of detection is qualitative and preferably to be used as quick determination of yes/no cases, more comprehensive and qualitative methods are needed for research purposes. 

Bahorun and colleagues describe the use of thin-layer chromatography (TLC) to determine total proanthocynidins, phenol, and flavonoid content of hawthorn extracts. High-performance liquid chromatography (HPLC) analysis using a UV detector at 280 nm for proanthocyanidins and phenolic acids, and 360 nm for flavonoids is also described (Bahorun et al., 1996). 

The determination of optimal reaction-conditions (greatly facilitated by the use of thin-layer chromatography) is often critical, as initial products may undergo further reactions this was demonstrated in syntheses of 2,3 4,5-dianhydro-D-iditol from 3,4-di-O-sulfonyl-D-mannitol derivatives.368 389... 

A series of precoated plates prepared from a variety of single or mixed adsorbants on glass, plastic, aluminium, and other supports are now commonly available. These precoated plates greatly simplify the use of thin-layer chromatography. 

IR spectroscopy is used for the qualitative identihcation of surfactants and for differentiating between them and nonsurfactant compounds. Prior to IR spectroscopy, however, separation of the organic compound complex into different fractions, performed by, e.g., the use of thin-layer chromatography, is required to obtain meaningful spectra. °" ° By comparing the IR spectra of the isolated fractions with IR spectra of standard compounds with regard to characteristic bands, the qualitative determination of surfactants in environmental samples is possible. The method is equally applicable to anionic, ° nonionic, °" and cationic surfactants.The prerequisite for a clear identification of surfactants, however, is the availability of suitable standards. Moreover, considerable experience and knowledge are needed to interpret IR spectra of environmental samples. 

The following constitutes a general guide to the use of thin layer chromatography (TLC). Pertinent reference sources on the subject include [1]-13]. The discussion here is focused on precoated plates, since these have largely supplanted homemade layers. For further information on the relationship between TLC and other types of chromatography - Basic Principles of Chromatography. 

In GPC of polymers it is desirable to avoid specific interactions between polymer and substrate. In the past few years there has been a very rapid increase in the use of thin layer chromatography (t.l.c.) for polymer analysis. In this technique it is possible to separate polymers either by size differences as in GPC or by chemical differences, thus making it extremely useful for analysis of polymer mixtures and copolymers. Applications of t.l.c. have been thoroughly reviewed. - Kamide et al. report studies of cellulose nitrate showing that the polymer can be dispersed on a t.l.c. plate according to either molar mass or nitrogen content. 

Roberson, J. (1991). The use of thin-layer chromatography in the analysis of drugs of abuse. In Analysis of Drugs of Abuse, T. A. Gough (Ed.). Wiley, Chichester, pp. 3-22. 

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