Simultaneous Determination of 226Ra and 228Ra in Water by Liquid Scintillation Spectrometry

Radium is a naturally occurring alkaline earth metal that is present in soils, water, plants, and foods in low concentrations. In the analysis of radium in trace amounts, co-precipitation is the favoured way of separating an element from its matrix. In this case, radium is co-precipitated with barium. The purity and yield of the extraction is controlled by adsorption onto the barium sulfate precipitate and pH manipulation controls the solubility of certain products. This technique enables the removal of interfering lead-210 to yield a purified radium source for analysis, which is done using liquid scintillation spectrometry. The analytical results of spiked water samples are in good agreement with the known activities of radium-226 and radium-228 standard reference materials. Minimum detectable limits for radium-226 and radium-228 are calculated to be 0.01 and 0.06 Bq L–1, respectively. The method provides a fast, reliable, and accurate alternative to traditional radium isotope analysis based on α and gamma spectrometry.