engleski

Determination of Sr-89, 90 in complex samples

Among all radionuclides which are released into nature one of the three most studied is 90Sr. Reason for this lies in the fact that radioactive strontium isotopes are highly radiotoxic fission products (especially 90Sr with long half life), and as such they were an interesting subject for various kinds of investigations, from their distribution and behavior in natural systems to their influence on human health. As a rule, the determination of radioactive strontium is complicated and time-consuming, especially if isotope 89Sr is present in sample. Therefore, the main purpose of this work is a describing and comparing the some novel procedures for “ rapid” radioactive strontium determination. In one procedure, strontium is isolated from samples on the column filled with Sr resin by binding of strontium to the resin and successive elution with HNO3. In the second method strontium and yttrium are bound on to anion exchange column from alcoholic solutions of nitric acid. The optimum mixture of alcohols for sample binding is a mixture of ethanol and methanol with the volume ratio 1:3. Strontium and yttrium are separated from Mg, Ca, K, and other elements by elution with 0.25M HNO3 in the mixture of ethanol and methanol. It is shown that the procedure with the Sr resin is simpler and faster in the phase of the isolation on the column in comparison with the procedure with the anion exchanger. The procedure with the mixed solvent anion exchange, however, enables the simultaneous isolation of yttrium and strontium and rapid determination of 89, 90Sr. The described methods were tested by determining of 89, 90Sr in different kind of samples (some obtained from Environmental Measurement Laboratory, USA). It is also shown that the efficiency of isolation on the column depends on and separation conditions on the both column ; as a rule, strontium recovery strongly depends on column dimension and kind of sample. Therefore it is showed how experimental data and theoretical models can be used for the calculation of the parameters that enables the estimation of optimum separation condition. A simple relation for the calculation of breakthrough volume, which defines the sample volume and eluent volume for optimal strontium isolation is proposed.

89; 90Sr isolation; anion exchanger; mixed solvent; Sr-resin; breakthrough volume calculation; optimization

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