Cation-exchange resin columns hydrogen-form

Procedure Pass 10 ml of urine through a cation-exchange resin column (Dowex 60-W-X4, 20-50 mesh, in the hydrogen form) and wash the column with 30 ml of distilled water. Elute the amino acids with 20 ml of concentrated ammonia solution. Evaporate this eluate to dryness in vacuo. To the residue add 1 ml of trifluoroacetic anhydride and 0.5 ml of trifluoroacetic acid, and allow the mixture to stand at room temperature for 20 minutes. Remove excess reagents with a stream of air and treat the oily residue with an ethereal solution of distilled diazomethane (DANGER Poisonous-explosive) for 15 minutes. Remove excess diazomethane (CAUTION ) with a stream of air. Dissolve the residue in methanol and inject a suitable aliquot part into the gas chromatograph. Figures 25 and 26 show results obtained by this procedure. 

To illustrate how different cations may be separated let us consider a column which is packed with a cation exchanger in the hydrogen form. As a solution containing M ions flows through the column the M ions will replace H" " ions on the resin according to the value of K. If only a small amount of the solution is used and it is washed down the column with pure water, all the M ions will eventually replace hydrogen ions, and will form a stationary adsorbed band. The distribution of the ions within this band will depend on the value of if large, the band will be narrow and concentrated if small, wide and diffuse. Thus, if a few ml of 0.1 moldm sodium chloride are placed on a column which is then washed with distilled water, the sodium ions will remain in a more or less narrow band near the top of the column and an equivalent amount of hydrochloric acid will be liberated to be eluted from the column. 

In 40 parts by volume of water is dissolved 0.6 part of 2, 3 -epimino-2 -deamino-3 -deoxykanamycin B, and in the presence of 9 parts by volume of Raney nickel the mixture is stirred while introducing hydrogen gas at a pressure of 100 kg/cm2 at 60°C for 6 h. After the reaction Raney nickel is separated by filtration. The Raney nickel is washed well with 300 parts by volume of 1 N-aqueous ammonia and the washing is added to the filtrate. The whole is concentrated to about 100 parts by volume. The precipitated insolubles are removed by filtration, and the pH of the supernatant is adjusted to about 5.0 with hydrochloric acid. The mixture is run onto a column of 50 ml of cation-exchange resin [Amberlite CG-50, NH4+-form]. 

Anion Analysis (Figure 9.6b). For anion analysis the analogous principles apply, only now the eluant is, for example, the hydroxide or mixed carbonate/bicarbonate ion and the suppressor column a cation exchange resin in the hydrogen form, thereby suppressing conductivity by the formation of water and dissolved carbon dioxide respectively. 

Hypophosphoric acid, H4P20g, can be prepared as a dihydrate from the solution obtained when Na2H2P20g is poured through a column of cation-exchange resin in its hydrogen form ... 

A small sample of water may be rapidly converted to deionized water (DI) using a combination of cation and anion exchange. In this example, the columns consist of a hydrogen-saturated cation-exchange resin followed by a hydroxyl-saturated anion-exchange resin. The process consists of first exchanging all the cations to a hydrogen form in the water sample ... 

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