Kinetic-spectrophotometric method for the determination of neodymium and mixtures of neodymium with lanthanum and cerium

A kinetic method is described for the determination of neodymium, based on its inhibitory effect on the acetonitrile-catalysed oxidation of Pyrocatechol Violet by hydrogen peroxide. The reaction rate was followed spectrophotometrically at 490 nm. The method allows the determination of neodymium in the concentration range 0.14–1.4 µg ml–1 with a relative standard deviation of about 4%. The effect of lanthanum and cerium on the reaction inhibited by neodymium, which is manifested by an increase in this effect, was used for their determination in mixtures with neodymium. Binary and ternary mixtures of neodymium, lanthanum and cerium were analysed with a relative standard deviation of up to 6.1%.