Automated extraction chromatographic radionuclide separation system for analysis of ⁹⁰Sr in seawater

After the Fukushima Dai-ichi nuclear power plant disaster, the demand for a rapid method for the detection of environmental radioactivity increased drastically. Since the development of extraction chromatography using resins, analytical methods have advanced significantly in terms of simplicity and required labor. Herein, a home-made automated separation system that is applicable radio-extraction chromatographic separation techniques is reported. A simple, rapid, and high-throughput method was developed using this home-made automated separation system to analyze radiostrontium in seawater in emergency and routine situations. For emergency situations, radiostrontium in seawater is pre-concentrated on a cation exchange resin and consecutively purified using the Sr-resin. Fifty minutes are required for the purification of ⁹⁰Sr in four samples (100 ml). The minimum detectable activity (MDA) for ⁹⁰Sr is 0.2 Bq kg^-1 at 100 min counting, with a recovery of 70% and counting efficiency of 95% in the scintillation mode. For routine monitoring, ⁹⁰Y that is in equilibrium with ⁹⁰Sr is first separated from the sample matrix using DGA. Treatment of 30 L of each seawater sample requires ~2 h. The MDA for this method is 0.3 mBq kg^-1 at 400 min counting with a recovery of 70% and counting efficiency of 67% in the Cerenkov mode. By employing the developed method, the measured ⁹⁰Sr in seawater collected from the coastal area of Korea is 0.92 ± 0.18 mBq kg^-1, which is comparable to that reported previously. The measurements were obtained using a liquid scintillation counter, and the entire separation process was performed by employing the home-made separation system.