Gels, thin layer chromatography

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. 

Infrared spectra were obtained with a Perkin-Elmer 1800 and a Nicolet Magna-IR 750 FTIR spectrophotometer, and the absorption frequencies are reported in wave numbers (cm4). NMR spectra were obtained with BZH-300 and CA-F-300 Bruker FTNMR 300 MHz spectrometers. Chloroform-d was used as solvent, and all chemical shifts are reported in parts per million downfield (positive) of the standard. H-NMR and 13C-NMR chemical shifts are reported relative to internal tetramethylsilane, while 19F-NMR chemical shifts are reported relative to internal fluorotrichloromethane, Rf values were obtained from silica gel thin-layer chromatography developed with a mixture of 1.5 mL methylene chloride and three drops of acetone. The number of hydrate water molecules was calculated from the integration of H-NMR spectra. 

Merck 60 F254 silica gel thin-layer chromatography (TLC) plates... 

Materials. The water used for all purposes was double-distilled (once with glassware) and deionized (final conductance was less than 1 X 10"6 ohm1 cm."1). Stearic acid (obtained from Sigma Chemical Co.) was at least 99% pure as determined by silica gel thin-layer chromatography (4), and the synthetic L-a(/ ,y-dipalmitoyl) lecithin was about 90% pure (see Ref. 13 for analysis). The ATP-14C and its derivatives were obtained from Nuclear-Chicago or New England Nuclear Corp. and were found to be 95-98% pure as determined by cellulose thin-layer chromatography (16). 

Chi is purified from chloroplast extracts, usually obtained from spinach leaves, by dioxane precipitation method (51) and conventional sugar column chromatography (52). For rapid and easy preparation, the method recently developed by Omata and Murata (53) is satisfactory synthetic (DEAE-) Sepharose is substituted for sugar on the column. Besides using spectroscopic criteria (52), the purity of Chi samples can be checked readily by means of silica-gel thin layer chromatography (54). Colorless contaminations in Chi... 

Silica-gel thin-layer chromatography plates (Fisher catalog 05-713-317) pH paper (1-11)... 

Activate a silica-gel thin-layer chromatography (TLC) plate by heating for 5 min in a 100°C oven. This procedure drives off excess moisture from the plate so that the TLC separation is more reproducible. 

Obtain a silica-gel thin-layer chromatography plate that has been activated in a 100°C oven for 5 to 10 min. On either side of the plate, make a small scratch in the silica matrix about 2 cm from the bottom of the plate. This will mark the position of the origin, along which the samples will be spotted. Do not mark on the plate with pencil. 

Silica-gel thin-layer chromatography plates (Fisher catalog 05-713-317)—Heat at 100°C for 10 min just before use. (Store dessicated at room temperature.) Twenty-five will be required we try to fit two groups on one plate. 

Silica-gel thin-layer chromatography plates—We purchase these from Fisher (catalog 05-713-317). The plates are prepared (activated) by heating in a 100°C oven for 5 to 10 min to remove any moisture from the matrix. Remove from the oven and store desiccated at room temperature until they are ready to be used. Approximately 2 5 plates will be required (1 plate/2 groups). 

The tripeptide was purified by Sephadex GIO filtration followed by silica-gel chromatography. The pure material did not react with ninhydrin because of the presence of N -terminal pyroglutamic acid. After silica-gel thin layer chromatography in several solvent systems, the product gave a single spot when detected with Pauly s reagent with overall yield of 13%. 

Fernando, W.P.N. Poole, C.F. Determination of kinetic parameters for precoated silica gel thin layer chromatography plates by forced flow development. J. Planar Chromatogr. 1991, 4, 278-287. 

On silica gel thin-layer chromatography (TLC) plates eluted with a mixture of cyclohexane-ethanol (97 3, by volume), vitamin Aj alcohol and re/ro-vita-min Ai alcohol (Rp values 0.10 and 0.09, respectively) are separated from the pair vitamin Aj acetate/re/ro-vi-tamin Aj acetate (Rp values 0.48 and 0.45, respectively) and vitamin Aj palmitate (Rp value 0.78) and anhy-drovitamin Aj (Rp value 0.87) [5]. Geometric isomers of retinol are separated on silica gel plates using... 

Synthesis of Maduramicin Monoamide with 1.6-Hexanediamine (M-C NH-A One gram of tritium-labeled maduramicin (specific activity 23 iCi/gm) was dissolved in 10 mL of toluene with 100 xL of triethylamine. Ethyl chloroformate (100 pL) was diluted in 15 mL of toluene and was added dropwise to the cold maduramicin solution and allowed to stir at 4 C for 30 minutes. A 10 fold molar excess of 1,6-hexanediamine (1.2 gm) was dissolved in 10 mL of toluene and added. After 11/2 hours of reaction at 4 C, ice cold water (4 C) was added to remove salts and clarify the toluene solution. The reaction product was monitored by silica gel thin-layer chromatography and radioactivity. Maduramicin monoamide with 1,6-hexanediamine (M-CgN ) was purified by silica gel column chromatography using a gradient of methanol in ethyl acetate with or without triethylamine as the mobile phase. The product was stored in toluene at 4 C. 

In I960 Stahl suggested the separation of PBO from pyrethrins by means of a silica gel thin-layer chromatography, followed by treatment with antimony trichloride, which produces a violet spot in the presence of PBO (Zweig and Sherma, 1973). 

The alkaloidal fraction was then further separated using preparative silica gel thin layer chromatography (TLC). The material was separated on Silica Gel 60 (0.25 mm, Merck) using cyclohexane chloroform diethylamine (5 4 1), and six discrete fractions were identified. The major alkaloid had an Rf of 0.43, and this fraction was by far the most active in the nicotinic receptor assay. This active fraction was then further characterized by mass spectrometry, proton and C13 NMR spectroscopy, and was identified as methylly-caconitine (MLA,Fig.l). It was found to have a Kinh value for displacing 3Hot-BGTX of less than 0.5 nM (Fig.2). 

Enzyme-linked immunosorbent assay (ELISA) methods for pectenotoxins are under development in several countries and a preliminary method has been reported [51-54], Silica gel thin layer chromatography (TLC) is useful to identify pectenotoxins in semipurihed samples [1,20,39] however, it is difficult to use the TLC for screening tests of toxins in crude bivalve extracts owing to the poor selectivity and sensitivity. 

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