The procedure for determination of strontuim-90 (=yttrium-90) by HDEHPextraction of yttrium-90 and counting the Cerenkov radiation in a liquid scintillation counter, is applicable for all kind of samples. Prior to analyses liquid samples are evaporated to dryness and ashed. Environmental and food samples are oven dried and ashed.
The ash is dissolved in 1 molar hydrochloric acid and, at pH 1.0-1.2 the yttrium-90 is extracted from the solution with 10% HDEHP. All mono and divalent ions will stay in the acid phase. Yttrium-90 is backextnlcted into 3 molar nitric acid and precipitated as hydroxide. The hydroxide precipitation is dissolved in 1 ml conc nitric acid, transferred to a liquid scintillation vial and the Cerenkov radiation from yttrium-90 is counted in a liquid counter.