Rapid determination of radium-224/226 in seawater sample by alpha spectrometry

摘要

A new radiochemical separation method has been developed for rapid determination of alpha-emitting radium isotopes in seawater samples. This method can be applied for the measurement of Ra-226 in seawater samples when Ra-224 is used as tracer for chemical recovery correction. Likewise, Ra-226 can also be added as tracer for the determination of Ra-224 in seawater sample. In the method, radium is first pre-concentrated with hydrous titanium oxide (HTiO) and is purified by combined anion/cation exchange column chromatographic separation. The radium in the eluate is then co-precipitated with HTiO, dissolved in 9 M H2SO4, and followed through a BaSO4 micro-precipitation step to prepare a thin-layer counting source to determine the activities of Ra-224/Ra-226 by alpha spectrometry. Replicate spike and blank samples were measured to evaluate the performance of the procedure. The minimum detectable activity concentration was determined to be 0.5 mBg.L-1 for Ra-226 and 0.4 mBg.L-1 for Ra-224 in 1 L of seawater sample with a counting time of 48 h. The method is a promising candidate for rapid measurement for alpha-emitting Ra isotopes in a large population of environment water samples. (C) 2017 Elsevier Ltd. All rights reserved.