N. Dacheux et J. Aupiais, DETERMINATION OF URANIUM, THORIUM, PLUTONIUM, AMERICIUM, AND CURIUM ULTRATRACES BY PHOTON ELECTRON REJECTING ALPHA-LIQUID SCINTILLATION, Analytical chemistry, 69(13), 1997, pp. 2275-2282
The determination of activities of thorium, uranium, plutonium, americ
ium, and curium at very low levels has been performed by a new a liqui
d scintillation system (PERALS, name registered to Ordela, Inc.). The
limit of detection has been determined for these nuclides with calcula
ted values often lower than those obtained by other methods, like ICPM
S/HP/Mistral, time-resolved laser-induced spectrofluorometry, and alph
a spectrometry. All the results obtained show that the PERALS system i
s a promising method for the determination of these activities at very
low levels. However, its energy resolution is inferior in comparison
to that obtained by a spectrometry. For this reason, we have developed
a process for separation of the five actinides as quickly and easily
as possible. For each actinide, the conditions required to obtain opti
mal extraction yields and a complete separation have been determined.
It is possible to perform the separation in only six extraction steps
and to measure activities as low as a few millibecquerels per liter in
dependently. This process has been applied with success to French gran
itic mineral or doped water and to complex media (biological samples l
ike urines). In this latter case, the extraction recoveries are not qu
antitative, and it is necessary to determine the recovery yields by la
beling with spikes like Th-230, U-232, Pu-236, Cm-248, and Gd-148.