Colorants thin-layer chromatography

Thin-Layer Chromatography (tic). Tic (126) is used widely for quahtative analysis and micro-quantity separation of amino acid mixtures. The amino acids detected are developed by ninhydrin coloring, except for proline and hydroxyproline. Isatia has been recommended for specific coloring of pToline (127). 

The moist cells were suspended in 750 parts of volume of ethanol and extracted by warming at 60°C for 1 hour. A total of 3 extractions were carried out in a similar manner and the extracts were pooled, diluted with water and further extracted three times with 1,000 parts of volume portions of n-hexane. The n-hexane layer was concentrated to dryness under reduced pressure to recover 4.12 parts of a yellow oil. This oily residue was dissolved in 6 parts by volume of benzene and passed through a column (500 parts by volume capacity) packed with Floridil (100 to 200 meshes). Elution was carried out using benzene and the eluate was collected in 10 parts by volume fractions. Each fraction was analyzed by thin-layer chromatography and color reaction and the fractions rich in ubiquinone-10 were pooled and concentrated under reduced pressure. By this procedure was obtained 0.562 part of a yellow oil. This product was dissolved in 5 parts by volume of chloroform, coated onto a thin layer plate of silica gel GF254 (silica gel with calcium sulfate) and developed with benzene. The fractions corresponding to ubiquinone-10 were extracted, whereby 0.054 part of a yellow oil was obtained. This oil was dissolved in 10 parts by volume of ethanol and allowed to cool, whereupon 0.029 part of yellow crystals of ubiquinone-10 were obtained, its melting point 4B°to 50°C. 

Analyses in the pg range, e.g., in water and oil, can be carried out with thin-layer chromatography [244]. After separation on the thin-layer plates, then by Dragendorff reagent, colored spots are measured with the help of a spectral photometer at 525 nm. 

An aliquot may be removed at this stage and analyzed by either gas chromatography or thin-layer chromatography to ensure that the reaction is complete. Benzobarrelene has a retention time of ca. 5 minutes in a gas chromatographic analysis under the conditions stated in Note 6, but with a column temperature of 104°. The completion of the reaction is also indicated by a purple coloration of the precipitated sodium chloride. 

The identification of the target colorant is done directly by UV-Vis spectrometry (if the colorant is unique) or by a previous separation from a mixture. The most available techniques are planar chromatography (paper chromatography and thin layer chromatography) and, especially, high performance liquid chromatography... 

Dichloromethane extraction of culture broth, thin layer chromatography of the extract, and visualization with 5% vanillin/sulfuric acid spray is effective for detecting cycloheximide in culture broth. Cycloheximide applied to TLC plates in amounts as low as 1 yg/spot will produce visible color with the vanillin spray. 

Two identification tests for oxytetracycline hydrochloride are given in the USP 28 [1], one being an ultraviolet absorption test and the other a color test. European Pharmacopoeia [2], British Pharmacopoeia (BP) 2003 [4], International Pharmacopoeia [5], and Pharmacopoeia of the People s Republic of China [6] described a thin-layer chromatography and color tests for identification of oxytetracycline hydrochloride and oxytetracycline dihydrate. For identification of oxytetracycline calcium, USP 28 [1] used Method II under identification of tetracycline <193>, whilst BP 2003 [4] described a TLC, color test, and calcium test as the method of identification. 

Examine the sample by thin-layer chromatography, using silica gel G R as the coating substance. Dissolve 10 mg of the substance to be examined in 4 mL of water R as a test solution, and dissolve 10 mg of penicillamine reference substance in 4 mL of water R as a reference solution. Apply 2 pL of each solution separately to the plate. Develop over a path of 10 cm using a mixture of 18 volumes of glacial acetic acid R, 18 volumes of water R, and 72 volumes of butanol R. Dry the plate at 100-105 °C for 5-10 min, and expose to iodine vapor for 5-10 min. The principal spot in the chromatogram obtained with the test solution is similar in position, color, and size to the principal spot in the chromatogram obtained with the reference. 

Experiment 39 The Thin-Layer Chromatography Analysis of Jelly Beans for Food Coloring... 

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. 

Color reactions are used in the laboratory in conjunction with thin-layer chromatography (TLC) — a routine and highly popular method for the analysis of explosives (for a full review, see Ref. [1, chapter 5, pp. 59—85] and Ref [2, chapter 2, pp. 33—41]). Spots on the TLC plates are visuaHzed by spraying the plates with appropriate color reagents. 

Procedures. Chromatographic Purification of Ozonization Products. Ozonization products from ethyl 10-undecenoate and 1-octene were chromatographed on silica gel columns (Baker) and eluted with 15 or 25% ether in petroleum ether (b.p., 30°-60°). Fractions were examined by thin-layer chromatography (TLC) on silica gel G Chroma-gram sheet eluted with 40% ether in petroleum ether. For development of ozonide and peroxide spots, 3% KI in 1% aqueous acetic acid spray was better than iodine. The spots (of iodine) faded, but a permanent record was made by Xerox copying. Color of die spots varied from light brown (ozonide) to purple-brown (hydroperoxide), and the rate of development of this color was related to structure (diperoxide > hydroperoxide > ozonide). 2,4-Dinitrophenylhydrazine spray revealed aldehyde spots and also reacted with ozonides and hydroperoxides. Fractions were evaporated at room temperature or below in a rotary evaporator. 

Thin layer chromatography (TLC) uses the same principles as GC or HPLC but is performed on a glass plate containing an adsorbent, such as silica or alumina, that attracts other molecules to its surface. A small portion of the sample to be analyzed is spotted on the plate. The plate is placed upright in a tank containing a small amount of solvent that then rises up the plate and separates the components of the sample. The separated components can be located with an ultraviolet lamp or by spraying the plate with chemicals to produce color. 

Seized samples of marijuana are analyzed in the laboratory using a color test, thin-layer chromatography, and a microscopic test. The Duquenois-Levine color test, although not specific for marijuana, is often used. Using the microscope one can see on the upper side of the marijuana leaf characteristic bear claw -shaped cystolithic hairs, which contain calcium carbonate. 

Although a filtered sample of the reaction mixture analyzed by nuclear magnetic resonance (chloroform-d) shows no more dihaloketone after a reaction time of 2 hours (excess of furan was discernible), the reaction mixture must be heated for an additional 2 hours to destroy traces of dihaloketone which make difficult the subsequent work-up and analytical thin-layer chromatography of the product mixture. When the reaction was carried out with less sodium iodide (33 g., 0.22 mole), the presence of diiodoketone in the final product was noted by formation of an iodine color and... 

Each column fraction is analyzed for lipid material by spotting on a 5 X 10 cm silica gel thin-layer plate and exposing it to iodine vapor as follows. Prepare seven tapered capillary tubes and use these to place a spot of each solution on the TLC plate. Put at least 10 capillary applications from a single fraction on a spot. Your final plate should then have seven spots, one for each fraction. Set the plate in an iodine chamber and allow it to remain for about 15 minutes or until some spots are yellow or red-brown. The presence of lipid in a fraction is indicated by the red-brown color. Retain all the column fractions that appear to have lipid. Each of these fractions will be analyzed in part B by thin-layer chromatography. 

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