ISO 23597:2023

This document specifies a titration method for the determination of rare earth content in 15 kinds of individual rare earth metals (lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium) and their oxides.
The determination ranges for the rare earth content in mass fraction are as follows:
—     rare earth metal: 98,0 % (mass fraction) to 99,5 % (mass fraction);
—     rare earth oxide: 95,0 % (mass fraction) to 99,5 % (mass fraction).
It does not apply to individual rare earth metals and their oxides when:
a)       the relative rare earth purity is less than 99,5 % in mass fraction;
b)       the total content of various (non-rare earth) metallic elements is greater than 0,5 % in mass fraction;
c)        the content of thorium, scandium or zinc is greater than 0,1 % in mass fraction.