Determination of neodymium in rare earth mixtures by fourth-derivative spectrophotometry

Abstract

The absorption spectra corresponding to the 4f electron transitions of the neodymium complex with xylenol orange and cetylpyridinium chloride in the presence of Triton X-100 are reported. The absorption by neodymium is increased by a factor of 666, compared with that of its chloride. Fourth-derivative spectra are used to increase the sensitivity and to eliminate interferences from other rare earth elements. Beer's law is obeyed for 1.4–7.2 μg Nd in 25 ml of solution. The relative standard deviation is 0.8% for 5.0 μg/25 ml ( n = 7). Detection limits are 5.0 ng ml −1 for Nd alone and 11.0 ng ml −1 in the presence of 45 ng of lanthanum. Satisfactory results were obtained for the determination of neodymium in rare earth mixtures.