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.