Silica-gel-G-plates

The literature reports [a]n +23.2° (c = l, aqueous 5N hydrochloric acid). The product was analyzed by the submitters. Analysis caleulated for C5H11NO2S C, 40.25 H, 7.43 N, 9.39 S, 21.49. Found C, 40.14 H, 7.42 N, 9.50 S, 21.52. The product was homogeneous according to thin-layer chromatograms on precoated silica gel G plates purchased from Analtech, Inc., Newark, Delaware, and developed with the following two solvent systems (solvents, volume ratios of solvents in the same order) 1-butanol-acetic acid-ethyl acetate-water, 1 1 1 1, Rf 0.49 1-butanol-acetic acid-pyridine-water, 15 3 10 12, R/0.51. 

Chloroform-methanol extracts of Borrelia burgdorferi were used for the identification of lipids and other related components that could help in the diagnosis of Lyme disease [58]. The provitamin D fraction of skin lipids of rats was purified by PTLC and further analyzed by UV, HPLC, GLC, and GC-MS. MS results indicated that this fraction contained a small amount of cholesterol, lathosterol, and two other unknown sterols in addition to 7-dehydrocholesterol [12]. Two fluorescent lipids extracted from bovine brain white matter were isolated by two-step PTLC using silica gel G plates [59]. PTLC has been used for the separation of sterols, free fatty acids, triacylglycerols, and sterol esters in lipids extracted from the pathogenic fungus Fusarium culmorum [60]. 

A Silica gel G plate is developed with a 15% aqueous solution of NaHS03. The Rf values in this system for dobutamine and 3-0-methyldobut-amine are 0.50 and 0.35, respectively (4). 

Thin Layer Chromatography. TLC analysis of the WSAP was accomplished By application to silica gel G plates at a concentration of 0.1 mg and development to 14 cm with chloroform-methanol-water (60 35 8). Prior to sulfuric acid-char treatment, five components were visibly resolved. Following such treatment a total of 10 components were visualized. Duplicate plates were divided into six zones, which were scraped, eluted with methanol and assayed at a concentration of 0.2 mg equivalents... 

The nature of the aromatic amine to form 17 complexes was important. On silica gel G plates and MCB-EDC as solvent PC-anisidine complex had lower migrations than PC-DPA or PC-DEA complexes... 

Exercises in thin-layer chromatography. Separation of amino acids. Prepare solutions of DL-alanine, L-leucine and L-lysine hydrochloride by dissolving 5 mg of each separately in 0.33 ml of distilled water, measured with a graduated 1 ml pipette (leucine may require warming to effect solution). Mix one drop of each solution to provide a mixture of the three amino acids and dilute the remainder of each solution to 1 ml to give solutions of the respective amino acids. The latter will contain about 5 pg of each amino acid per pi. Apply approximately 0.5 pi of each of the solutions to a Silica Gel G plate and allow to dry in the air (i.e. until the spots are no longer visible). 

These reactions may be monitored by t.l.c. analysis on Silica gel G plates using toluene methanol, 9 1, as solvent the components may be located by iodine vapour (p. 204). 

TLC is the preferred separation method because of its high separation efficiency, rapidity, and large variety of detection possibilities. Usually 0.5 mm thick silica-gel-G-plates are used, activated at 120°C for 30 min. in a supersaturated atmosphere. Well-known of poly techniques such as multiple separation in opposite or parallel direction allow the selectivities to be further increased. The selection of an appropriate mobile phases determines the efficiency of separation. Advantage is taken of specific interactions and also of reactivity with the stabilizers under investigation. 

Cohen and Wheals [334] determined ten hydrolysable carbamate and substituted urea herbicides in soil in amounts down to 0.001-0.05 ppm. In this method, a solution of the herbicide-containing extract of the soil is spotted onto a silica gel G plate and developed with hexane acetone (5 1). The plate is sprayed with 1-fluoro-l,4-dinitrobenzene in acetone and heated to 190 °C to produce the 2,4-dinitrophenyl derivative of the herbicide amine moiety acetone extracts of the areas of interest are subjected to gas chromatography. 

The TLC system for identification of phenytoin in capsules and tablets is composed of silica gel G plate (Analtech) and chloroform-isopropyl alcohol-amnonia (45-45-10). Rf = 0.6. Masond43 has given the Rf values for Phenytoin in the following systems on silica gel GF plate ... 

The ethyl acetate extracts of the reaction mixture were concentrated under nitrogen and applied to 250p Silica Gel G plates (Analtech). The solvent used for the mobile phase was CHCl3-ethyl acetate (8 2). The plates were examined under an ultraviolet lamp and the bands were scraped clear into separate tubes. The products were then dissolved in ethyl acetate or n-butanol and analyzed by UV-visible spectrophotometry and the spectra from 254-450 nm were compared with those of authentic standards. Radioactivity levels were determined and the products were analyzed by mass spectrometry. 

Reaction conditions -l C-Aminof luorene (0.15 mM), H202 (0.15 mM), peroxidase (10 pg), 0.1 M Tris-HCl buffer pH 6.5 with and without DNA (3 mg) + 2,3,6-tri-CH3-phenol (0.15 mM) were incubated for 1 minute. Ascorbate (0.2 mM) was added to stop the reaction and the mixture was extracted with ethyl acetate. The extract was concentrated and chromatographed on Silica Gel G plates with CHCl3-ethyl acetate (8 2) as solvent. 

Mosinska [106] has described a semi-quantitative thin layer chromatographic method for the determination of trichlorphon in potable water. The sample is extracted with redistilled chloroform. The extract is dried with sodium sulphate, reduced in volume to 5mL in vacuo and then evaporated to dryness in a stream of air. The residue is dissolved in acetone and chromatographed on chloride-free silica gel G plates (activated at 100°C for lh) with benzene-methanol (17 3) as solvent. The spots, revealed with ammoniacal silver nitrate in acetone, are compared with those of standards for semi-quantitative determination. The detection limit is 0.02mg L 1 and the efficiency of extraction is 70%. 

According to the Indian Pharmacopoeia, 2,3-dimethylaniline is examined by TLC using a silica gel G plate, and a mixture of 90 volumes of toluene, 25 volumes of dioxane, and 1 volume of 18 M ammonia as the mobile phase. Apply 40 pL of each of the two solutions in a mixture of 3 volumes of chloroform and 1 volume of methanol containing (1) 2.5% w/v of the substance being examined separately to the plate, and (2) 0.00025% w/v of 2,3-dimethylaniline. After removal of the plate, dry it in a current of warm air. Spray the dried plate with ethanolic sulfuric acid (20%), heat at... 

The compounds represented in this facsimile were as follows Nl, neutral lipids (cholesterol, triacylglycerol) PE, phosphatidylethanolamine PS, phos-phatidylserine PI, phosphatidylinositol PC, phosphatidylcholine Sph, sphingomyelin X, gangliosides, polyphosphoinositides, lysophosphatidic acids. The chromatography was done on silica gel G plates with chloroform-methanol-ester (65 35 31, v/v) as the solvent. 

Another approach to identification of the phosphoinositides by TLC was developed by Gonzalez-Sastro and Folch-Pi (1968). In order to avoid the possible influence of Ca2+ on the mobility of PIP2, these investigators used silica gel H, which is devoid of CaS04 binder used in silica gel G plates, and included 1% potassium oxalate to bind any traces of Ca2+. In a solvent system of chloroform-methanol-4N NH4OH (9 7 2, v/v), the following Rf values were reported PI, 0.78 PIP, 0.36 and PIP2, 0.14. 

Some years later, Billah and Lapetina (1982) employed silica gel G plates impregnated with 1% potassium oxalate containing 2 mM EDTA. In a solvent system of chloroform-methanol-4N NH4OH (45 35 10, v/v), the following... 

Progress of the elution can be monitored by placing aliquots of the eluent on a mini-silica gel G plate, spraying with sulfuric acid and then charring. This is only one example of a solvent system that works for this particular situation. Many other combinations could be tried and again, as stated many times, it depends on the goal of the particular experiment. 

If an examination of the chemical nature of the products is desired, then an aliquot of the reaction mixture can be subjected to thin-layer chromatography on silica gel G plates. In a solvent system of chloroform-methanol-water (65 35 7, v/v), the liberated fatty acids will migrate to an Rf near 0.90, the unreacted substrate to an Rf near 0.42, and the lysophosphatidylcholine to an Rf near 0.18. These compounds can be visualized by spraying the plate with TNS reagent (see Chapter 3) and then exposing to ultraviolet light. The... 

The water-rich upper phase is removed and assayed for organic phosphorus. This will provide a quantitative evaluation of the efficiency of the enzymatic cleavage. The chloroform-rich lower layer is washed well with methanol-water (10 9, v/v). An aliquot of this chloroform-soluble fraction can be tested qualitatively on a small silica gel G plate for the presence of... 

Another spray used to detect the vinyl ether phosphoglycerides on thin layer chromatograms is one containing 2,4-dinitrophenylhydrazine in 2N HC1 or 2 N H2S04. However, when using this spray, it is first necessary to run the sample, spotted on a precoated silica gel G plate, 250 pm, in chloroform-methanol-water (65 35 7, v/v). At the end of the development, the plate is allowed to air dry and then is exposed to HC1 fumes (usually the plate is suspended above a dish containing 12 N (concentrated) HC1 for several minutes). It is then sprayed with the dinitrophenylhydrazine reagent. If an aldehyde is present, a yellow spot will appear within a few minutes at most. 

The reaction mixture was filtered to remove the enzyme particles and the solvent evaporated on a rotary evaporator yielding a yellow oil. The oil was dissolved in 100 mL diethyl ether and the low molecular weight phenolic products were extracted into an equal volume of 5% NaOH solution. The residual ether soluble fraction contained primarily Pummerer s ketone and higher molecular weight phenolics while the base-soluble fraction contained the p-cresol and the biscresol. Further purification was performed by preparative thin layer chromatography (TLC) (1 mm silica gel G plates, Analtech, Newark, DE) with a solvent system of diethyl ether heptane (2 1). Rf values were 0.81 for biscresol and 0.63 for Pummerer s ketone. 

The extract is examined using silica gel G plates and ethyl acetate as the mobile phase (System TF, p. 168). Score the plates vertically to bring about an even movement of the mobile phase, and score a horizontal line 10 cm from the bottom of die plate to mark the distance travelled by the solvent front Dissolve the residue from the extract in 100 jiil of acetone and immediately apply 30 )li1 to die plate at the same time apply lO-pl portions of each reference solution. After development, dry the plate with a hot-air blower. 

Tang [16] described an improved method for thin layer chromatographic identification of compound buclizine. Compound buclizine contains mainly buclizine hydrochloride, bromhexine hydrochloride, and promethazine hydrochloride. A 20 ml portion of sample solution was made alkaline with 0.05 M sodium hydroxide (2.5 ml) and extracted with chloroform (5 ml). Standard solution of buclizine hydrochloride, bromhexine, hydrochloride, and promethazine together or separately were similarly prepared. The chloroform solution were spotted on to Silica gel G plates (previously treated with 0.5% sodium hydroxymethylcellu-lose solution and activated at 100 °C for 1 h) with chloroform methanol ... 

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