Oscar. Menis

Flame spectra of sc, y and rare-earth elements

Abstract Flame spectra are presented of sandium, yttrium and the rare-earth elements, except cerium and promethium. These elements were extracted with a solution of 2-thenoyltrifluoroacetone (TTA) in 4-methyl-2-pentanone (hexone) and their spectra in the organic medium were subsequently recorded by means of a flame spectrophotometer. The precise wave length and relative spectral intensity of each line and band are tabulated. Included, also, are the 1/2-band widths and the relative spectral interferences of other elements of the group with the emission of measurement of the bands and lines listed. Operating conditions, applicability and limitations of the method in the estimation of some of the rare-earth elements are given

Spectrophotometric methods for the determination of osmium-II: Extraction and determination of osmium in situ with 1.5-diphenylcarbohydrazide

Abstract A method has been developed for the spectrophotometric determination of microgram quantities of osmium in uranyl sulphate solutions. The osmium is oxidised to osmium tetroxide, then extracted with chloroform. The extracts are added to an ethanolic solution of 1:5-diphenylcarbohydrazide. A blue-violet coloured reaction product is formed which exhibits maximum absorbancy at 560 mμ. After a period of 2 hr for colour development the molar absorbancy index is about 31,000. Beers law is adhered to over a range of 30 to 100 μg of osmium with a coefficient of variation of about 4%. A study was made of the effects of foreign substances and only chloride and octovalent ruthenium were found to interfere. Both of these interfering ions can be eliminated.

Determination of aluminium in thorium oxide and a separation scheme for interfering ions

Abstract A method is presented for the separation and subsequent estimation of 0.5 to 150μg of aluminium in thorium oxide which contains corrosion products of steel and other impurities. The aluminium is separated from thorium, iron, zirconium and some other elements by extraction of these elements with a hexone solution of thenoyltrifluoroacetone (TTA). Aluminium is then extracted with 8-quinolinol and chloroform in the presence of hydrogen peroxide, sodium cyanide, and nitrilotriacetic acid, which mask interfering ions that are not removed by the TTA extraction. In view of the effectiveness of the separation scheme in eliminating interferences, the aluminium can be measured either fluorometrically or spectrophotometrically, depending on the quantity to be determined. When the thorium oxide also contains manganese and cobalt, a double extraction, using TTA and sodium diethyldithiocarbamate, is required to remove the interfering ions before the aluminium can be successfully determined as the quinolinate.

Spectrophotometric methods for the determination of osmium-III: Reaction of osmium tetroxide with 1:5-diphenylcarbo- hydrazide in aqueous solutions followed by extraction of the complex

Abstract -A spectrophotometric method has been developed which is applicable to the determination of extremely small quantities of osmium. Osmium is oxidised to the octovalent state, then added to an acidic aqueous solution containing 1:5-diphenylcarbohydrazide (DPC). After heating the aqueous solution to 65°, the osmium-DPC complex is extracted with chloroform. A molar absorbancy index of about 150,000 is obtained. From 7 to 25 μg of osmium can be determined with a coefficient of variation of 6%. It was established that FeIII, CuII, RuIII and AuIII seriously interfere in the determination of osmium by this method, while CrVI, NiII, MoVI, IrIII and chloride interfere only when present in relatively high concentrations.

SPECTROPHOTOMETRIC DETERMINATION OF SILICON IN THORIUM OXIDE

Abstract A method is described for the spcctrophotometric determination of microgram quantities of silicon in the presence of thorium. Thorium oxide is dissolved by heating it at 70 to 8o°C in 4M HNO3 that contains 2 drops of HF. Under these conditions, no silicon is lost through volatilization. The silicon is estimated as the blue ailicomolybdate complex. Under the conditions selected for development of color, a precipitate of thorium molybdate is obtained ; the thorium molybdate is, however, dissolved without affecting the color of the complex by the addition of tartrate and adjusting the pH of the solution to 3.0. The lower limit of detection is about 5 p.p.m. of silicon.

SOME APPLICATIONS OF HIGH-FREQUENCY TITRIMETRY

Abstract A parallel transmission line oscillator operating at 190 Mc/s was demonstrated to be a useful instrument for the performance of high-frequency titrations. The end point is established by graphically recording either the oscillator grid current or the IR drop, which is produced by passing this current through a load resistor, versus the volume of titrant and extrapolating the two segments of the titration graph to a point of intersection. The instrument has been utilized for the titration of Th, free acid and sulfate in solutions of high ionic strength. The method is of particular value in titrating solutions containing substances which mask the color change of indicators or otherwise interfere with visual titrations. Furthermore, it appears to be adaptable for use in the titration of radioactive materials by remote control.

Evaluation of Flame Photometry For The Determination of Elements of The Rare-Earth Group

Summary Because of the occurrence of several of the rare-earth elements and closely related elements as important constituents of the fission products from nuclear reactors, methods for the determination of these elements are essential in the evaluation of control and reprocessing procedures, as well as in the operation of reactors. A study was therefore made of the complex flame spectra of the rare-earth elements and the closely related elements, Y and Sc, for the purpose of evaluating, extending and improving flame photometric methods for the estimation of these elements. Flame photometric data were developed by the use of organic extracts of the chelates of the several elements. The areas in which flame photometry may be applied and limitations imposed by mutual interference are discussed elsewhere. †