Fractionation of Lanthanum-Cerium(III) and Lanthanum-Praseodymium Mixtures. Precipitation from Homogeneous Solution

Abstract

mean values ranged from iz0.0007 to *0.0040%. Results may be duplicated on the same sample with an average precision of about zkO.0016%.Some of the observations of others (5') regarding the nature of the reagent have been confirmed. Thus a t 90" C. maximum color developed after 3 hours, while a t 80" C. a t least 5 hours were required. The colored complex is stable for a t least several hours. The e~clusion of moisture from the reaction medium is necessary. Although this situation is not ideal, it did not present any serious difficulties.The reagent is both selective and sensitive to boron and a maximum concentration of 10 micrograms of boron per 10 ml. should not be exceeded in the solution used for final photometric measurement.The normal time required to complete a determination is approximately 4 to 5 hours.