Silica fractions eluted from

Millson [113] investigated components of sewage sludge and found elementary sulphur in the hydrocarbon fractions eluted from liquid adsorption columns. By using a solid adsorbent such as alumina, silica gel, or Florisil, and heptane as eluent, the sulphur could be separated from weakly adsorbed hydrocarbons, e.g. squalene or biphenyl, but not from more strongly adsorbed hydrocarbons such as phenyldodecane. 

To a stirred solution of ethyl l-(NG-nitro-L-arginyl)-4-methyl-2-piperidinecarboxylate hydrochloride in 200 ml of chloroform were added in turn 18.5 g of triethylamine, and 14.7 g of 3-methyl-8-quinolinesulfonyl chloride at 5°C, and stirring was continued for 3 hours at room temperature. At the end of this period, the solution was washed twice with 50 ml of water. The chloroform solution was dried over anhydrous sodium sulfate. Upon evaporation of the solvent, the residue was chromatographed on 50 g of silica gel packed in chloroform, washed with chloroform and eluted with 3% methanol-chloroform. The fraction eluted from 3% methanol-chloroform was evaporated to give 32.1 g (91%) of ethyl l-[NG-nitro-N2-(3-methyl-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylate in the form of an amorphous solid. 

The first three solvent systems eluted from silica over 17% of the applied asphaltenes while the quantity of neutral asphaltenes from ion exchanger chromatography, that is, those components that passed both the anion and cation exchanger columns, amounted to 20% of the material. This is a reasonably close agreement between fractions of asphaltene separated by two different methods. At first sight, this suggests that these fractions are very similar however, comparison of MWs of these fractions does not support this conclusion. 

The functionality distribution of HTPB 134> can be obtained using the double detection procedure after derivatization of the OH groups with phenyl isocyanate. However, a true fractionation can been obtained by stepwise elution from silica gel n8,120) and, coupled with GPC, it enables establishment of the relationship between functionality and molecular weight distributions. Precipitation fractionation can also be used... 

The avidin content of the fractions eluted from the ion exchange column were determined by reverse phase HPLC analysis using an Alltech octyl-bonded silica column, a Perkin Elmer Series 410 quaternary solvent... 

Although we have yet to work out an HPLC method for the complete purification of SIF, by Incorporating silica gel chromatography, we have greatly improved (based on UV and NMR spectroscopy see below) our initial purification. Fig. 1 demonstrates the ability of the active fraction, eluted from a Biol Sil A column, to inhibit the In vivo light-triggered ATPase activity of the D. sallna CFi. As was the case for the partially... 

Radioactive spot is located by autoradiography and iodinated product is eluted from silica gel by ethanol and stored after distribution into small fractions at -20°C until use. 

Column chromatography is very useful for sample preparation. The fractions eluted from the NH2-bonded silica column with hexane as solvent showed some polar molecules, and increasing solvent polarity eluted a series of aliphatics and aromatics with carbon numbers exceeding C50. The analysis also showed that the extent of alkylation decreased with increasing severity of the coal liquefaction process [19]. 

Preparation of cholesta-5,7-diene-ia,3/3-diol a solution of 500 mg of the 1,4-cyclized adduct of cholesta-5,7-dien-3/3-ol-ia,2a-epoxideand 4-phenyl-1,2,4-triazoline-3,5-dione in 40 ml of tetrahydrofuran is added dropwise under agitation to a solution of 600 mg of lithium aluminum hydride in 30 ml of THF. Then, the reaction mixture liquid Is gently refluxed and boiled for 1 hour and cooled, and a saturated aqueous solution of sodium sulfate is added to the reaction mixture to decompose excessive lithium aluminum hydride. The organic solvent layer is separated and dried, and the solvent Is distilled. The residue Is purified by chromatography using a column packed with silica gel. Fractions eluted with ether-hexane (7 3 v/v) are collected, and recrystallization from the methanol gives 400 mg of cholesta-5,7-diene-la, 3/3-diol. 

After having been dried over sodium suifate and evaporated under vacuum, this extract gives as a solid residue 14.7 g of crude 7-cyanoacetylamino-cephalosporanic acid which is purified by chromatography on 30 times its own weight of silica gel. The fractions eluted with chloroform plus acetone (7 3) furnish a product which crystallizes from acetone plus ether in the form of needles melting at 168° to 170°C with decomposition. 

Cu(OAc), H20 (0.75 g, 3.7 mmol) was added to a refluxing solution of metal-free 1,4,8,11.15,18,22,25-octa(propyloxy)phthalocyanine (0.1 g, 0.1 mmol) in BuOH (5 mL). The solution was maintained at reflux for 0.5 h, cooled, and chromatographed (silica gel, CH2C12 and Et20). The green-blue fraction eluted first was crystallized from a slowly evaporating solution in CH2Cl2/py yield 0.086 g (81 %). 

Purification of luciferin (Rudie etal., 1976). The luciferin fractions from the DEAE-cellulose chromatography of luciferase were combined and concentrated in a freeze-dryer. The concentrated solution was saturated with ammonium sulfate, and extracted with methyl acetate. The methyl acetate layer was dried with anhydrous sodium sulfate, concentrated to a small volume, then applied on a column of silica gel (2 x 18 cm). The luciferin adsorbed on the column was eluted with methyl acetate. Peak fractions of luciferin were combined, flash evaporated, and the residue was extracted with methanol. The methanol extract was concentrated (1 ml), then chromatographed on a column of SephadexLH-20 (2 x 80 cm) usingmethanol asthe solvent. The luciferin fractions eluted were combined and flash evaporated. The residue was... 

After elution from the SPE cartridges, the eluents will be evaporated slowly under nitrogen gas. The concentrated samples containing metolachlor will be analyzed by GC/MS while the fractions containing the polar metabolites will be analyzed by HPLC. Both the GC and HPLC will be equipped with chiral columns. For GC/MS, a fused silica column coated with tert-butyldimethylsilyl-P-cyclodextrin will be used. This column has been shown to partially separate metolachlor isomers (13). 

In this paper we report upon a detailed examination of the hexane extract (Fraction A) of 21 kg of the roots of II. littoralis. The dry hexane extract was subjected to chromatography on a silica gel column and eluted with a hexane/ethyl ether gradient. From the different fractions eluted, three crystalline compounds were isolated two of which are new natural products. The compounds described herein are tentatively named compounds II and III. The additional compound will be discussed in a future paper. 

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