Spectrophotometric Determination of Rare Earths with a New Chromogenic Reagent Dibromo-p-methyl-bromosulfonazo

A new method for determination of cerium subgroup rare earths was studied and reported. It was found that rare earth ions could react with a new chromogenic reagent dibromo p methyl bromosulfonazo in hydrochloric acid medium to form a 1:2 stable blue complex with an absorption maximum at 642 nm. Beer`s law is obeyed for the rare earths in the range of 0～1 0μg/mL. The method was applied to determination of the total amount of cerium subgroup rare earths in steel samples with satisfactory results.