Fast method of determination of ²²⁶Ra and ⁹⁰Sr from aqueous matrices using Mn6 composite sorbent

A sorbent based on manganese oxides bonded to the SiO₂ matrix was prepared using aqueous alkaline silicate solutions. The composite sorbent was tested for the possibility of separation of ²²⁶Ra and ⁹⁰ Sr from aqueous solutions, also influence pH, competing ions and the possibility of desorption selected radionuclides. Radiochemical yields were determined using tracer radionuclides ¹³³Ba for ²²⁶Ra, ⁸⁵Sr for ⁹⁰Sr and measured on the HPGe detector. ¹³³Ba was eluted from Mn6 sorbent with 4 mol/L HNO₃ in yields ranging from (62.6-89.9)%. ⁸⁵Sr was eluted with 0.05 mol dm^-3 chelaton III at pH 11, the radiochemical yields ranged between 56.92 and 72.31%. Volume activities of ²²⁶Ra were measured on the 576A ORTEC alpha spectrometer and compared with the ²²⁶Ra volume limit values in mineral waters set by the Ministry of Health of the SR. ⁹⁰Sr volume activities were determined after an increase of ⁹⁰Y on a TriCarb 3100 TR liquid scintillation spectrometer, ⁹⁰Sr volume activity values were smaller than MDA (0.0002 Bq dm^-3). (authors)