Richard B. Hahn

The direct weighing of ziorconium tetramandelate

Abstract The non-stoichiometry of zirconium tetramandelate precipitates is explained by the presence of basic salts of varying composition. For reproducible results the zirconium tetramandelate should be precipitated from hot. strongly acid solution by the dropwise addition of mandelic acid.

Determination of radiophosphorus by solvent-extraction

Abstract A procedure is given for the determination of radiophosphorus in the presence of other activities. Potassium phosphate is added as carrier and the phosphorus is extracted as phospho-molybdic acid into a butanol-chloroform mixture. The activity is back-extracted into ammonium hydroxide and the phosphate is precipitated as magnesium ammonium phosphate. This may be air-dried or ignited to magnesium pyrophosphate for counting. The method is rapid, accurate, and free from interference by other radionuclides. Especially noteworthy is the excellent separation from radioarsenic.

Analytical uses of bromanilic acid

Abstract Bromanilic acid (2,5-dibromo-3,6-dihydroxyquinone) precipitates barium, calcium and strontium quantitatively from weakly acid solution, and forms a coloured complex with zirconyl ions in perchloric add solution. The complex exhibits maximum absorbance at a wavelength of 335 mμ. Beers law is obeyed in the range from 0.0 to 3.5 ppm of zirconium. Optimum results are obtained in solutions 2.8 M in perchloric acid. The effect of various diverse ions has been investigated. Hafnium gives results identical with zirconium. Other interfering ions are Fe III , Th IV , UO 2 II , Ti IV , phosphate, oxalate, fluoride and sulphate. Errors caused by varying amounts of these ions have been determined. A procedure for the determination of zirconium is given. Bromanilic acid is a more sensitive reagent than chloranilic acid for the determination of zirconium, and can be used over a slightly greater range.

A study of the separation of phosphate ion from arsenate ion by solvent extraction

Abstract The results presented confirm the postulate of Keggin that oxygen-containing materials are good solvents for heteropoly acids. The results also show that none of the solvents examined will completely separate phosphate ion from arsenate ion with a single extraction. The butanol-chloroform system is studied extensively. The results show that as the percentage of butanol is increased in the mixed solvent, the percentage of phosphate and arsenate extracted also increases. Of the various concentrations of butanol studied, the 10% concentration shows the most promise as a selective extractant for phosphate consistant with a high yield. The results also show that the amount of arsenate ion extracted with any given concentration of butanol is relatively independent of the concentration of phosphate ion in the system.

DETERMINATION OF RADIOACTIVE COBALT IN MIXTURES OF RADIONUCLIDES

Abstract A detailed procedure for the separation of radioeobalt from other active material is described. Precipitation as the mercurithiocyanate and as the anthranilate have been compared, and the latter has been shown to be somewhat preferable.

Removal of phosphate ion by ion-exchange

Abstract A method for the removal of the phosphate ion is described. This is accomplished by the use of an anion exchanger, Amberlite IRA-400. The method is rapid and no foreign cations are introduced in the process.

Precipitation of zinc sulfide by the hydrolysis of thioacetamide

Abstract Zinc can be precipitated quantitavely as zinc sulphide using thioacetamide in a weakly acid solution. This is accomplished by carrying out the reaction in a sealed tube at 120 0 . The method, however, does not give a good separation from cobalt. Best separations are obtained by using a sulfate-bisulfate buffer containing ammonium thiocyanate with hydrogen sulfide as precipitant.

Separation and determination of radioactive caesium in milk.

A method is given for the separation and determination of radiocaesium in fluid milk. Caesium is separated from organic material and interfering ions by passage of the milk sample through a cation-exchanger in the lithium form. It is eluted from this column with 6M hydrochloric acid. Two methods are given for the recovery of radiocaesium from the eluate. It may be precipitated with silico-tungstic acid and then converted into caesium perchlorate for counting or weighing. Alternatively, the eluate is passed through a small column of ammonium phosphomolybdate, which quantitatively sorbs the radiocaesium, the activity of which is determined by putting the column in a well-type scintillation counter and measuring the activity. Approximately 90% of the radiocaesium is recovered.

Precipitation of zinc sulfide by hydrolysis of thioacetamide in the presence of hydrazine hydrochloride

Abstract Zinc sulfide can be precipitated quantitatively from solutions buffered at pH 2 using thioacetamidehydrazine hydrochloride mixtures as precipitants. Optimum results are obtained using equimolar quantities of thioacetamide and hydrazine hydrochloride. Coprecipitation of cobalt sulfide was studied using citrate-citric acid, and sulfate-bisulfate buffers. Optimum separations are achieved using a sulfate-bisulfate buffer containing ammonium thiocyanate.

Sodium hydrogen diglycolate as a reference buffer

Abstract A 0.2 M solution of sodium hydrogen diglycolate, easily prepared from the commercially available salt, has a pH of 3.40 ± 0.02. The pH of this solution is constant over a wide temperature range. A 0.2 M sodium hydrogen diglycolate solution has a high buffer capacity. The pH is not changed greatly by addition of salt up to a concentration of 0.05 M . Dilution of the 0.2 M solution by a factor of two does not affect the pH more than ± 0.02 pH units. The solution may be stored for considerable time with little variation in pH. Sodium hydrogen diglycolate is non-hygroscopic and available in primary standard grade. Of the common metal ions only Hg 2 2+ is precipitated by the buffer. These properties make sodium hydrogen diglycolate useful as a reference buffer for standardisation of electrode systems, and as a buffer in various analytical and biochemical procedures.