Abstract

The efficiency and applicability of the solid phase extraction disk method in a 226Ra analysis were examined by the gamma ray spectrometer (GRS) method using a Marinelli beaker and the liquid scintillation counter (LSC) method for groundwater. The recovered 226Ra, which was filtered by the solid phase extraction disk, was analyzed using gamma ray spectrometer The disks, which were pretreated for caulking the daughter nuclide, were sealed with polyethylene film. Distilled water was used for the blank value of the 226Ra activity. The recovery values of 214Bi and 214Pb in the solid phase extraction disk, which used 226Ra standard material, were 80% (295.21 Kev) and 104% (351.92 Kev), respectively, which were higher than 75% determined by the LSC. The injection of nitrogen gas into the measuring chamber reduced the interference values by about 10%. The detection limits of the 226Ra activity in a blank sample of 5 L were 0.17~0.40 pCi/L after 80,000 seconds of measuring time. The relationship of the 226Ra activity in the solid phase extraction disk method and in the LSC method in seven groundwater samples showed a correlation coefficient value 0.987, which implies the applicability of the solid phase extraction disk method. The results showed that 226Ra activity in groundwater using the solid phase extraction disk method has the following benefits: simple pretreatment, time saving, high recovery values, a low detection limit, and so on. Compared with the LSC method and the GRS method using the Marinelli beaker for the 226Ra analysis, the solid phase extraction disk method could be useful in groundwater samples with low levels of activities of radionuclides because the method is not restricted by the volume of the sample.