Diphenic acid as an analytical reagent

Summary Diphenic acid can separate thorium completely from moderate amounts of ferrous iron and titanium in almost neutral solutions. As the reagent forms quantitative precipitates with ferric iron and zirconium, workable methods for their separation from thorium and their co-determinations in a mixture with the help of this reagent have also been developed. The reagent can separate thorium from zirconium by precipitating the latter below p_h2, and the same from iron(ic) can be accomplished by the use of ascorbic acid as a masking agent. Ferric iron can be precipitated from solution containing ascorbic acid, by the ammonium salt of the reagent. A convenient process for the estimation and separation of zirconium, thorium, iron(ic) and titanium, when present in a mixture, has also been described, which involves the proper control ofph and the use of ascorbic acid as a complexing agent for ferric iron.My sincere thanks are due to Dr. A.K. Mukherjee of the Indian Association for the Cultivation of Science, Calcutta for his valuable suggestions and to Dr. A. K. Ghosal, Principal, Darjeeling Government College for providing laboratory facilities.