EXTRACTION OF RADIUM ISOTOPES FROM SOME COASTAL SEAWATER SAMPLES IN EGYPT METHOD VALIDATION

Abstract

A radiochemical separation of Ra isotopeswas carried out to determine the activity levels of radium (226Ra and 228Ra)in seawater samples, as well as providing a base-line data on background radiation in the investigated locations. Seawatersamples were collected from selected sites along the coasts. The water samples were analyzed for radium isotopes (Ra-226 & Ra-228) using alpha and liquid scintillation detectors.Development steps were applied to the radioanalysis procedure by using calcium phosphate co-precipitation and the addition of isopropanol. Quality assurance and method validation of the developed procedure was carried out to assure the results. The obtained results were within the uncertainty level ± 5%. Quality control steps were applied through the efficiency calibration of the detectors, the estimation of uncertainties, the use of blanks and the comparison with other laboratories.For comparison, selected samples were measured by gamma spectrometry using high purity germanium detector, after radiochemical separation of the isotopes with ion-exchange chromatography using a strong cation exchange resin, and the activity concentrations of 228Ra were comparable with those analyzed by the LSC. The average activity concentrations of 226Ra and228Ra in the Mediterranean seawater samples were found to be 166.8 and 500.6 mBq/L respectively, while in the Red seawater samples were 13.0 and 176.7 mBq/L respectively. The maximum value of radium activity was found at RasElBarr estuary, where the River Nile fresh water mixes with the coastal seawater. On the basis of the current results, we may conclude that the radium activities in the investigated seawater samples are well comparable to the corresponding reported values in literature.