Comparison alpha and gamma spectrometry method for the determination of pb-210 in freshwater sediment

Abstract

The comparison of methodology from and -spectrometry methods, has been made for freshwater sediment. The differences of precisions 18% and 15% were found for ? and -ray spectrometry respectively. Results from the analysis of certified reference materials (IAEA-326, 327) showed good agreement with recommended values and data available in the literature. Thus an alternative methodology based on alpha/gamma activity ratio was developed and tested using different samples. The method is based on the determination of total -activity (46.53 keV peak associate with Pb-210) and the total -activity present in the aliquot. Differences between methods could be caused by different behaviors of Pb-210 and Po-210 (used for alpha measurement) in the freshwater sediment. In gamma spectrometry errors may arise when many gamma emitters are measured simultaneously and their activity peaks overlap. In alpha spectrometry chemical separation of Po-210 may result in analytical error due to incomplete sample dissolution. Pb-210 activities derived by alpha and gamma methods are shown to agree within counting error. The inherent compatibility of analytical results based on alpha or gamma techniques is established. Nevertheless, the choice of an alternate method to determine the freshwater sediment, criteria to time, comfortable convenient and budget.