Keith E. Burke

The determination of fluorine in rare earth fluorides by high temperature hydrolysis

The technique of pyrohydrolysis has been applied to the determination of fluorine in the fluorides of scandium, yttrium, and the lanthanons. These fluorides have been divided into two classes according to their rate of hydrolysls. Lutetium, ytterbium, cerium (III), scandium. gadolinium, terbium, dysprosium, holmium, erbium, and thulium auorides can be hydrolyzed in 30 min or less. Yttrium. lanthanum, praseodymium. neodymlum, samarium, and europium fluorides require from 45 to 150 min for complete hydrolysis. Accelerators, such as uranium oxide (U/sub 3/C/sub 8/), chromium(UI) oxide. and a mixture of these oxides have been used successfully to reduce the time required for quantitative hydrolysis of the fluorides in the latter group. The use of the correct accelerator reduces the hydrolysis time to 30 min or less for all these fluorides except lanthanum, praseodymium, and neodymium. (auth)

Determination of microgram quantities of silver in aluminium-, iron-, and nickel-base alloys.

Trace quantities of silver in commercial nickel and its alloys are quantitatively extracted from 10% hydrochloric acid medium containing 2% ascorbic acid and 9% potassium iodide by a 5% solution of tri-n-octylphosphine oxide in 4-methylpentan-2-one (MIBK). The MIBK-extract containing the silver is then nebulized directly into an atomic-absorption flame. The sensitivity for the determination of silver in MIBK is about 6 times that for aqueous media. The proposed technique is accurate, rapid, and has a standard deviation of +/- 0.025 ppm at the 1 ppm level. The limit of detection is 0.2 ppm of silver. The method is also applicable to a number of elements in aluminium- and iron-base alloys.

A chemical concentration x-ray determination of selenium in copper-, nickel-and iron-base alloys.

A method is described for the determination of selenium in various metals and alloys at concentrations of 3-100ppm. A chemical separation is made by filtration after reduction of the selenious acid to elemental selenium with hydroxylamine hydrochloride. The pure selenium product is readily analysed by X-ray fluorescence; the method is free from errors due to matrix effects. The relative standard deviation is 6 % for a copper-nickel alloy at the 60 ppm level.

Determination of boron in nickel-base alloys by the dianthrimide method.

The dianthrimide method for the determination of boron in iron and low-alloy steels may be applied to nickel-base materials. The sample is dissolved, without any loss of boron, by hydrochloric and sulphuric acids and the resulting boric acid determined spectrophotometrically with dianthrimide. Background corrections are necessary to compensate for the absorbance from ions such as nickel and iron.

The Use of Ammonium Perchlorate with the Hydrogen-Argon-Entrained Air Flame in Atomic Absorption Spectroscopy

The use of ammonium perchlorate increased the usefulness of the hydrogenargon-entrained air (H2AA) flame. Arsenic, lead, tin, copper, bismuth, cobalt, iron, nickel, antimony, zinc, and selenium were studied. Copper, cobalt, iron, and nickel gave no signal in the relatively low temperature of the H2AA flame. The presence of ammonium perchlorate produced a signal which allowed these elements to be readily detected with a response greater than is obtained with an acetylene-air flame. The presence of a copper, iron, or nickel matrix obliterates the signal from elements studied in the H2AA flame. The presence of ammonium perchlorate does not completely eliminate the matrix effect.