DETERMINATION OF NEODYMIUM, HOLMIUM AND ERBIUM IN MIXED RARE-EARTHS BY NORFLOXACIN

Norfloxacin (NFX) is proposed as reagent for the derivative spectropho tometric determination of neodymium, holmium and erbium in mixed rare earths. The absorption spec tra of 4f electron transitions of the syst ems of neodymium, holmium and erbium complexes with norfloxacin in pre sence of cetylpyridinium chloride were studied by normal and derivativ e spectra. The absorption bands found normally at 575 nm for neodymium , 450 nm for holmium and 523 nm for erbium were enhanced markedly. Usi ng the second derivative spectrum, Beer's Law is obeyed from 5.0 x 10( -5) similar to 2.5 x 10(-4) mol dm(-3) for neodymium, holmium and erbi um. The relative standard deviations are 1.0, 1.4 and 1.1% for 6.9 x 1 0(-5) mol dm(-3) of neodymium, 6.1 x 10(-5) mol dm(-3) of holmium and 6.0 x 10(-5) mol dm(-3) of erbium, respectively. A method for the dire ct determination of neodymium, holmium and erbium in mixtures of rare earth elements with good accuracy and selectivity, is described.