Determination of neodymium, holmium and erbium in mixed rare earths by norfloxacin

Abstract

Norfloxacin (NFX) is proposed as reagent for the derivative spectrophotometric determination of neodymium, holmium and erbium in mixed rare earths. The absorption spectra of 4f electron transitions of the systems of neodymium, holmium and erbium complexes with norfloxacin in presence of cetylpyridinium chloride were studied by normal and derivative spectra. The absorption bands found normally at 575 nm for neodymium, 450 nm for holmium and 523 nm for erbium were enhanced markedly. Using the second derivative spectrum, Beer’s Law is obeyed from 5.0 × 10–5∼ 2.5 × 10–4 mol dm–3 for neodymium, holmium and erbium. The relative standard deviations are 1.0, 1.4 and 1.1% for 6.9 × 10–5 mol dm–3 of neodymium, 6.1 × 10–5 mol dm–3 of holmium and 6.0 × 10–5 mol dm–3 of erbium, respectively. A method for the direct determination of neodymium, holmium and erbium in mixtures of rare earth elements with good accuracy and selectivity, is described.