Column chromatography monitoring

Bi-functional radio-analytical scheme, based on exchange and extraction column chromatography, which provides the reliable information on molybdenum and uranium contents in biological materials has been elaborated. The contribution of uranium fission reaction has been strictly monitored. The uncertainty of the results of Mo determination by the presented method is very low. 

A solution of 1.0 g (33 mmol) of the mixture of heptofuranoside diastereomers (14) in 5 ntL of THE is stirred in an ice-water bath. 3.4 mL of 1 M soln ofTBAF (3.4 mmol) in THF are added, and Ihe reaction is monitored by TLC (CHCI,/CH, OH, 9 1). After ca. 15 min, the reaction mixture is carefully neutralized with dil sulfuric acid, then diluted with water and extracted with CHC13. The extract is dried over Na,S04 and concentrated to give an off-white solid which is a single stereoisomer (by NMR spectroscopy). Column chromatography gives the inositol as a white solid yield 0.61 g (70%) mp 186-187 C (benzene/CH,OH) [a]D + 118 (c = 03, CH, OH). 

A solution of Pd(OAc)2 (0.05 mmol) and bis(diphenylphosphino)ethane (0.05 mmol) in acetonitrile (1 ml) was heated gently to reflux, at which time a solution of the silyl enol ether (1 mmol) and diallyl carbonate (2 mmol) in MeCN (4 ml) was added in one portion. The mixture was heated under reflux for 1-3 h, the course of reaction being monitored by t.l.c. or g.l.c. analysis. On completion, the cooled reaction solution was filtered through fluorosil. The pure a/ -unsaturated compound was isolated by column chromatography on silica gel (70-95%). 

The major attribute that distinguishes planar techniques from column chromatography is that in the former separation and detection are discontinuous ( offline )- In column chromatography analytes are carried through the entire column and monitored at the end, usually by flow-through detectors measuring changes in some physical characteristics of the effluent (optical... 

Thin-layer chromatography is employed in many areas of QC and routine monitoring of product quality [458]. Fluorescence scanning, densitometry or videodensitometry are used for quantification. Not all polymer additives are amenable to TLC analysis. Some fatty acid amides are virtually insoluble in organic solvents and cannot be isolated by thin-layer or column chromatography. 

The pattern of metabolites in bile (animals only) and in urine have been investigated using column chromatography (Amberlite XAD 2 and Sephadex DEAE), tic and reversed phase HPLC in combination with radioactivity monitoring. 

A mixture of rhodium II) acetate (228 mg, 0.516 mmol), the imidazolidinone (1.70 g, 6.15 mmol), and dry chlorobenzene (20 mL) is heated under reflux for 18 h in a flask fitted with a Soxhlet extraction apparatus into which a thimble is placed containing an oven-dried mixture of sodium carbonate and sand (2 1, 5 g). The progress of the ligand-exchange reaction can be monitored by HPLC (p-Bondapak-CN column, methanol). The resulting blue solution is concentrated under reduced pressure, and the residue is purified by column chromatography (reversed phase silica, Bakerbond Cyano 40 mm prep. LC packing, methanol). 

Stearyl bromide (5.5 mmol) and triphenylphosphine (5.8 mmol) were heated under reflux for 20 hours in 30 mL anhydrous xylene. Upon completion of the reaction (as monitored by thin-layer chromatography) the solvent was removed followed by purifying the obtained crude yellowish oil by silica gel column chromatography using methanohchloroform (5 95) as an eluent. Purified STPP, obtained as colorless oil, crystallized on standing and was recrystallized from ether to yield pure STPP in 35% to 45 /o yields. 

Cuts from the silica gel column were incorporated into artificial diets optimized for several economically-important agricultural pest insects, the pink bollworm Pectinophora gossypiella> the tobacco budworm Heliothis virescens> the corn earworm H. zea and the fall armyworm Spodoptera frugiperda. > Monitoring with this artificial diet bioassay, further column chromatography and preparative TLC on silica gel in diethylether-petrol yielded five... 

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