An-Najah Staff

Spectrophotometric methods are presented for the determination of 0.04–5 mg of europium in rare earth mixtures, following a group separation, or in lanthanide compounds. Europium(III) is selectively reduced on a Jones reductor to europium(II) which in turn reduces molybdophosphoric acid to a molybdenum blue. The absorbance is measured at 810 nm in aqueous solution or at 790 nm after extraction into n-amyl alcohol; optimal reaction conditions and times are reported. Other rare earth elements, and chloride, bromide, perchlorate, acetate and sulphate, are without effect when present in gram amounts but nitrate and iodide must be absent. The method is applied to the determination of europium in various lanthanide oxides and bastnaesite.