Determination of thorium with organic reagents: uses of some aryl fatty acids

Phenylacetic-, phenylpropionic- and 1-naphthylacetic acids show definite promise as precipitating agents for the gravimetric determination of thorium. They can separate thorium from cerite earth and monazite sand, from solutions having thoria: rare earth oxide ratio up to 1 : 40, 1 : 16 and 1 : 14 respectively, by a double precipitation method. Foreign ions such as calcium, barium, strontium, titanium, zinc etc. do not interfere in the determination, of thorium by these reagents. As the thorium salts of these three acids are basic in nature, each possessing an entirely different composition, the determination of thorium by direct weighing of the precipitates is not possible and in each case the ignition of the precipitate to thoria is essential.