engleski

Simultaneous use of anion exchanger and Sr resin for efficient strontium isolatin from complex matrices

Among all radionuclides which are released into the nature one of the most studied is 90Sr. Reason is that radioactive strontium isotopes are highly radiotoxic fission products (especially 90Sr with long half-life), and as such they are an interesting subject for various investigations, from their distribution and behavior in natural systems, to their influence on human health. As a rule, a determination of radioactive strontium is complicated and time-consuming, especially if isotope 89Sr is present in the sample. The determination requires isolation of small amounts of strontium from complex matrices, its separation from large quantities of calcium (and other elements), and the detection of radioactive isotopes on the available instruments. The most difficult step is separation of Sr from Ca due to their similarities in chemical behavior. For this purpose, in a standard procedure, a method of precipitation with fuming nitric acid is used. Due to its aggressiveness, this method can be replaced with a method of chromatographic separation on a specific Sr resin. The Sr resin enables highly efficient separation of Sr from Ca and other elements. Therefore, the resin is increasingly used in the analysis of radioactive strontium in different kinds of samples. In practice, it is found that the efficiency of strontium isolation depends on the concentration of Ca, K, Na, and other present elements. It decreases with the increase of their concentration above certain limits. If efficiency of isolation (recovery) is reduced, the detection limit (MDA) will increase. In the case of low level activity determination, it will significantly expand uncertainty of determination. The decrease of recovery can be prevented by increasing the amount of the Sr resin used for isolation. However, the Sr resin may lose capacity during usage so desired effect can be lost. Sr can also be separated from Ca and a number of elements on anion exchange column using alcoholic solution of nitric acid. Unlike the Sr resin, anion exchanger does not lose capacity hence it can compensate disadvantages of the Sr resin. Therefore, the main aim of this work is developement of a robust and efficient method of strontium isolation from different types of samples. It involves simultaneous use of both resins. Also, the impact of the most abundant element concentrations in natural samples on the efficiency of strontium isolation will be examined. Special attention will be given to the separation of Rb from Sr and other elements in combination of both resins. Rb has several radioactive isotopes that could interfere with the determination of 89, 90Sr and should be separated prior detection. On the other hand, their mutual separation is important in isotope dating analysis.

strontium; separation; recovery; anion exchange

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