Separation of Sr from Ca, Ba and Ra by means of Ca(OH)2 and Ba(Ra)Cl2 or Ba(Ra)SO4 for the determination of radiostrontium Original Research Article

A simple procedure is developed to separate Sr from a large amount of Ca, which relies on the insolubility of Ca(OH)2 in alkaline solution. Calcium is quantitatively separated from Sr and more than 95% of Sr is recovered from a sample with as much as 50 g of Ca and a Ca/Sr mole ratio of 250. A new procedure for the separation of Sr from Ba and Ra is also investigated, which is based on the difference in solubility of the chlorides of Sr, Ba and Ra in HCl media. In 9.5 mol l−1 HCl or 7.5 mol l−1 HCl–10% acetone media, >97% of Ba and Ra can be removed by Ba(Ra)Cl2 precipitation, and >94% of Sr was recovered. In the determination of 90Sr by measuring 90Y, the separation of Ra and Ba can easily be carried out by precipitation of Ba and Ra as Ba(Ra)SO4, while Y can be quantitatively recovered in the solution. By this method, a further separation of 90Y from radiostrontium can be completed. The new separation procedure has been successfully used for the determination of 90Sr in samples with high Ca content, such as 45 l of seawater and 200 l of drinking water. The analytical quality of the results is comparable to that of the traditional method using fuming nitric acid and BaCrO4 precipitation.