US EPA

1437674 

Journal Article 

Rapid method for Ra-226 and Ra-228 analysis in water samples 

Maxwell, SL III 

2006 

Yes 

Journal of Radioanalytical and Nuclear Chemistry
ISSN: 0236-5731
EISSN: 1588-2780 

270 

3 

651-655 

10.1007/s10967-006-0469-y 

WOS:000242148200022 

The measurement of radium isotopes in natural waters is
important for oceanographic studies and for public health reasons. Radium-226 (T1/2 = 1620 y) is
one of the most toxic of the long-lived alpha-emitters present in the environment due to its long
life and its tendency to concentrate in bones, which increases the internal radiation dose of
individuals. The analysis of Ra-226 and Ra-228 in natural waters can be tedious and time-
consuming. Different sample preparation methods are often required to prepare Ra-226 and Ra-228
for separate analyses. A rapid method has been developed at the Savannah River Environmental
Laboratory that effectively separates both Ra-226 and Ra-228 ( via Ac-228) for assay. This method
uses MnO2 Resin from Eichrom Technologies (Darien, IL, USA) to preconcentrate Ra-226 and Ra-228
rapidly from water samples, along with Ba-133 tracer. DGA Resin (R) ( Eichrom) and Ln-Resin (R) (
Eichrom) are employed in tandem to prepare Ra-226 for assay by alpha-spectrometry and to
determine Ra-228 via the measurement of Ac-228 by gas proportional counting. After
preconcentration, the manganese dioxide is dissolved from the resin and passed through stacked
Ln-Resin-DGA Resin cartridges that remove uranium and thorium interferences and retain Ac-228 on
DGA Resin. The eluate that passed through this column is evaporated, redissolved in a lower
acidity and passed through Ln-Resin again to further remove interferences before performing a
barium sulfate microprecipitation. The Ac-228 is stripped from the resin, collected using cerium
fluoride microprecipitation and counted by gas proportional counting. By using vacuum box
cartridge technology with rapid flow rates, sample preparation time is minimized.