Third-derivative spectrophotometric determination of neodymium and erbium in mixed rare earths with 2-(diphenylacetyl)indan-1,3-dione and dodecyl benzenesulfonic acid sodium salt

The absorption spectra of 4f electron transitions of neodymium and erbium complexes with 2-(diphenylacetyl)indan-1,3-dione and dodecylbenzenesulfonic acid sodium salt have been studied by normal and derivative spectrophotometry. The use of third-derivative spectra both eliminates the interference from other REEs and enhances the sensitivity for neodymium and erbium. Beer's law is obeyed for ⩽21.6 µg cm–3 of neodymium and ⩽25.1 µg cm–3 of erbium. The detection limits (with a signal-to-noise ratio of 2) are 0.28 and 0.77 µg cm–3 for neodymium and erbium, respectively. A method for the direct determination of neodymium and erbium in mixed REEs and lanthanide–based samples with good accuracy and selectivity is described.