Abstract:
226Ra is a highly toxic radionuclide, and according to the Chinese national standard GB 5749—2022, its activity in drinking water must not exceed 1 Bq/L. Additionally,
226Ra serves as a geochemical tracer in oceanographic studies. To meet the monitoring requirements for
226Ra, this paper systematically summarize the pre-concentration and radiochemical separation methods for
226Ra in water samples, with a focus on discussing the advantages and disadvantages of radiation measurement techniques and mass spectrometry(MS) techniques for analyzing
226Ra. Pre-concentration methods include co-precipitation, evaporation, and adsorption. Co-precipitation, with its simplicity and cost-effectiveness, is well-suited for treating environmental water samples of up to 10 L in volume. For large volume water such as oceans and lakes, manganese polymer adsorption enables in-situ enrichment of Ra isotopes. Radiochemical separation methods include co-precipitation, solvent extraction, ion-exchange chromatography, and extraction chromatography, with the choice of method depending on subsequent analytical techniques. Radiometric methods such as radon emanation, alpha counting, and liquid scintillation counting(LSC) only require simple separation using coprecipitation and solvent extraction. However, alpha spectrometry and MS analysis demand more rigorous Ba removal using chromatographic techniques. Ion exchange chromatography is cost-efficient and widely used in laboratories, while novel extraction chromatographic columns(e.g., TK100 and AnaLig®Ra-01) enable selective Ra adsorption, simplifying separation workflows. Radiometric methods are widely applied for
226Ra monitoring due to their high sensitivity and low cost. LSC, combined with extraction chromatography, can enable automated
226Ra monitoring. Alpha spectrometry offers detection limits below 1 mBq/L, meeting the requirements for routine environmental monitoring. MS techniques, such as ICP-MS, provide rapid analysis, with each sample taking approximately five minutes, making them suitable for emergency assessments, though their high-cost limits routine use. Future research should focus on developing low-cost, high-selectivity extraction materials to streamline separation processes. Integrating radiometric methods with MS techniques could further enhance analytical efficiency and accuracy, supporting both environmental monitoring and emergency response efforts.