Chemistry Reference
In-Depth Information
tAbLe 9.5
Plutonium Isotope separations in Flow systems using Aliquat 336 Liquid
Anion exchange Chemistry on teVA-Resin
Year
Purpose/Approach
Detection
References
2000
Pu determinations in sediments using on-line tandem
Sr-Resin and TEVA-Resin columns in PrepLab system
SF-ICP-MS
56
2002
Pu determinations in seawater using on-line tandem Sr-Resin
and TEVA-Resin columns in PrepLab system
SF-ICP-MS
57
2004
Pu and Np determinations in environmental samples using
on-line column separation in PrepLab system
SF-ICP-MS
55
2007
Pu determinations in samples with high U levels, with
on-line separation and preconcentration using FI system
ICP-MS
50
2008
Pu determinations in urine with on-line separation and
preconcentration using FI system
SF-ICP-MS
143
exchanger in TEVA-Resin.
99
Tc in the anionic pertechnetate form,
99
Tc O
−
, is retained
on the resin under neutral to weakly acidic conditions, and eluted using strong acids.
The extraction equilibrium is shown in Equation 9.1, where A
+
indicates the quater-
nary ammonium group and the bar above a species indicates that it is immobilized
on the resin.
TcOANO
−
+ (
+
−
)
(
ATcO
+
−
)
+
NO
−
(9.1)
4
3
4
3
In 0.1 M HNO
3
solution, pertechnetate ion is retained with capacity factor
k
′
~10
4
.
30
The capacity factor decreases markedly with increasing nitric acid concen-
tration (
k
′ ~2 in 8 M HNO
3
)
30
and, after washing the column with dilute nitric acid,
the retained Tc(VII) can be eluted using 6-12 M HNO
3
. This separation is selective,
with most metal ions being removed during the column wash. However, tetravalent
actinides can be retained along with
99
Tc. Tetravalent Pu retention is significant even
in dilute nitric acid (capacity factor ~50 in 0.1 M HNO
3
). However, by incorporating
a suitable complexing reagent in the wash solution, actinide retention on TEVA-
Resin can be lowered.
Hollenbach et al. captured
99
Tc from standards or soil sample digestates on a
TEVA-Resin column for on-line purification and preconcentration prior to ICP-MS
determination.
49
A wash solution of 0.5 M HNO
3
was used to remove interferences
prior to elution with 8 M HNO
3
solution. A Re isotope, which behaves similarly to
pertechnetate on TEVA-Resin, was used as an internal standard. Recoveries from
the column varied from 97 to 99.5%, and columns could be reused over a hundred
times. The use of the on-line column separation reduced detection limits by 10-fold
and alleviated matrix and isobaric interferences compared to direct sample injec-
tion. This pioneering study adapted FIAS-200 and FIAS-400 FI systems to per-
form sample injection and extraction-chromatographic separations upstream from
the ICP-MS.
