Strontium (Sr) is a bone-seeking element, as are calcium and several other alkaline earth elements. Therefore, the presence of calcium causes major interference in the radiochemical analysis of bone samples for Sr-90. *Eichrom's prepacked columns with their Sr-spec resin are widely used to separate Sr from calcium in different kinds of materials. However, methods to separate Sr in large size bone samples with high calcium interference were not readily available. The Idaho National Laboratory (INL) analyzed large size marine bone samples (15 g) for Sr-90 as a part of an environmental project. The routine procedure used at INL took several clean-up steps over two weeks to separate calcium from Sr. Since Eichrom's Sr-resin has a much larger separation factor for Sr than for other interfering alkali and alkaline earth metals, a method was developed with this Sr-resin to separate Sr in bone samples. The samples were dissolved in HNO3 using the INL procedure. The solution containing the Sr fraction was loaded onto a column containing 3.6 g of Sr resin, which had first been conditioned with 4 M HNO₃. The molarity of the load solution was adjusted to between 4 and 8 where the separation of strontium over calcium is maximized. The Sr was eluted with 0.05 M HNO₃. This new method separated calcium from strontium in these samples in a few hours. The recovery of Sr was verified by Sr-85 tracer and the average tracer yield was >90%, indicating that this separation method was quite effective. The details of the experiment will be discussed.

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