DETERMINATION OF LOW CONCENTRATIONS OF AMERICIUM AND CURIUM BY PHOTONELECTRON REJECTING ALPHA-LIQUID SCINTILLATION/

The determination of very low activities of americium and curium has b een performed by a new analytical method based on alpha liquid scintil lation (PERALS(R)). The detection limit has been determined for severa l americium and curium isotopes. For both actinides, the values calcul ated are lower than those of other methods like inductively coupled pl asma mass spectrometry (ICPMS), time-resolved laser-induced spectroflu orimetry or alpha spectrometry. The conditions required to obtain opti mal extraction yields during the liquid-liquid extraction step have be en determined in several media. All the results obtained show that the PERALS system is a promising method for the determination of low alph a-emitter activities. Indeed, it is possible to detect activities as l ow as a few mBql(-1). The procedure has been applied with success to F rench granitic-mineral-doped water and to complex media (biological sa mples like urines, mineral samples,...). In this latter case, the extr action is not quantitative: it is then necessary to determine the reco very yields by labeling. Attempts to use Am-243 as a spike of Am-241 w ere unsuccessful because of the low difference in energy of a particle s for both nuclides (ca. 210 keV) in comparison with the PERALS resolu tion. On the contrary, labeling with Cm-246 or Cm-248 for Cm-244 and G d-148 for all americium and curium isotopes is possible and discussed in this paper. (C) 1998 Elsevier Science B.V.