Determination of strontium-90 in milk by means of yttrium-90 extraction with tributylphosphate

Opisana je vrlo jednostavna i relativno kratka metoda određivanja stroncija-90 u mlijeku metodom ekstrakcije itrija-90 tributilfosfatom iz slabo dušično kisele otopine pepela mlijeka u koji se doda CaO gotovo do zasićenja. Prikazani su efekti zajedničke ekstrakcije i sutaloženja kalcija i željeza na talogu itrijeva hidroksida. Proučavan je i utjecaj koncentracije fosfata na ekstrakciju itrija tributilfosfatom. Određeni su dekontaminacioni faktori za 144Ce, 106Ru, 95Zr + 95Nb, 137Cs, 85Sr te moguće smetnje 91Y i njegovog uklanjanja pri mjerenju radioaktivnosti 90Y. Dati su rezultati analize umjetno i prirodno kontaminiranih uzoraka mlijeka sa 90Sr.A simple and relatively quick method for the determination of strontium-90 in milk is described. The method is based on the proferential extraction of yttrium-90 with tributylphosphate from a weak nitric acid solution of milk ash to which is added CaO. The effects of calcium, iron and phosphates on the determination of yttrium carrier yield and on the distribution coefficients of yttrium-90 are discussed. The radioactive interferences of Ce144, Ru106, Zr95, Cs137 and Sr65 in the determination of Y90 activity are dealt with. Results of strontium determination in Sr90 spiked milk and in naturally contaminated milk are presented