Elution from ion-exchange resin

In 1955 the next step was announced. Very intense helium ion bombardment of tiny targets of E253 produced a few spontaneously fissionable atoms which eluted from ion-exchange resins in the eka-thulium position. This was evidence that element 101 had been found. Only seventeen atoms of this element were produced. It showed a half-life of between one-half and several hours. The name mendelevium (symbol... 

Separation of transuranic elements by elution from ion exchange resins... 

Wu, P. L., and D. A. Caldas Conversion of glutamic acid to 2-pyrrolidone-5-carboxylic acid in plant extracts during elution from ion-exchange resins. An. Acad. Brasil. Cienc. 44, 273 (1972). 

Figure 2-5 Elution of proteins from ion-exchange resins by altering pH or ionic strength.

Eermium coprecipitates with lanthanide fluorides and hydroxides, showing it to form lanthanide-like Em + ions. These elute from cation-exchange resins slightly before Es +, whilst its chloride and thiocyanate complexes are eluted from anionic exchange resins just... 

The ionization of boric acid is enhanced in solutions containing carbohydrates (143). This effect is variable, apparently depending upon the individual complexing ability of the sugar. Khym and Zill (144) have used this effect to separate sugars by removing their borate complexes from ion-exchange resins in columns by differential elution with acid developers... 

Acetaldehyde can be isolated and identified by the characteristic melting points of the crystalline compounds formed with hydrazines, semicarbazides, etc these derivatives of aldehydes can be separated by paper and column chromatography (104,113). Acetaldehyde has been separated quantitatively from other carbonyl compounds on an ion-exchange resin in the bisulfite form the aldehyde is then eluted from the column with a solution of sodium chloride (114). In larger quantities, acetaldehyde may be isolated by passing the vapor into ether, then saturating with dry ammonia acetaldehyde—ammonia crystallizes from the solution. Reactions with bisulfite, hydrazines, oximes, semicarb azides, and 5,5-dimethyl-1,3-cyclohexanedione [126-81 -8] (dimedone) have also been used to isolate acetaldehyde from various solutions. 

Ion-exchange separations can also be made by the use of a polymer with exchangeable anions in this case, the lanthanide or actinide elements must be initially present as complex ions (11,12). The anion-exchange resins Dowex-1 (a copolymer of styrene and divinylben2ene with quaternary ammonium groups) and Amherlite IRA-400 (a quaternary ammonium polystyrene) have been used successfully. The order of elution is often the reverse of that from cationic-exchange resins. 

The newest process to be developed oxidizes the brine with CI2 and then treats the solution with an ion-exchange resin the iodine is adsorbed in the form of polyiodide which can be eluted with alkali followed by NaCl to regenerate the column. About 65% of the iodine consumed in the world comes from brines. 

Dichlorodibenzo- -dioxin. 2-Bromo-4-chlorophenol (31 grams, 0.15 mole) and solid potassium hydroxide (8.4 grams, 0.13 mole) were dissolved in methanol and evaporated to dryness under reduced pressure. The residue was mixed with 50 ml of bEEE, 0.5 ml of ethylene diacetate, and 200 mg of copper catalyst. The turbid mixture was stirred and heated at 200°C for 15 hours. Cooling produced a thick slurry which was transferred into the 500-ml reservoir of a liquid chromatographic column (1.5 X 25 cm) packed with acetate ion exchange resin (Bio-Rad, AG1-X2, 200-400 mesh). The product was eluted from the column with 3 liters of chloroform. After evaporation, the residue was heated at 170°C/2 mm for 14 hours in a 300-cc Nestor-Faust sublimer. The identity of the sublimed product (14 grams, 74% yield) was confirmed by mass spectrometry and x-ray diffraction. Product purity was estimated at 99- -% by GLC (electron capture detector). 

The dichlorodibenzo-p-dioxin component was isolated by passing a dioxane solution of the mixture through acetate ion exchange resin to remove phenolics. The eluted product was recrystallized from benzene. The x-ray powder diffraction pattern of the precipitate was identical with that of 2,7-dichlorodibenzo-p-dioxin. Analysis of the mother liquor by GLC showed a singular peak consistent with 2,7-dichlorodibenzo-p-dioxin. The mother liquor was cooled to 5°C and yielded transparent crystals. This material had an x-ray diffraction pattern congruent to a sample of 2,8-dichlorodibenzo-p-dioxin obtained from A. E. Pohland (FDA). The two patterns were quite distinct from each other 14, 15). 

HPLC) for phenolic acids analysis. When procedure (ii) was applied, the ion-exchange resin was separated from the methanol phase and eluted with three 40 ml aliquots of 80% methanol. The resin bead eluates were evaporated to dryness and subjected to spectrophotometry (Shimadzu UV 160 spectrophotometer) for total phenolics and high-performance liquid chromatography (HPLC) for phenolic acids analysis. 

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