analysis of actinide elements from large samples henrieta dulaiova guebuem kim bill burnett florida...
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Analysis of Actinide Elements from Large Samples
Henrieta DulaiovaGuebuem Kim
Bill BurnettFlorida State University
andE. Philip Horwitz
PG Research Foundation
Need for Large Volumes
•Achieve very low MDA's for environmental monitoring
•Specialized scientific studies often require large volumes to obtain necessary sensitivity, e.g., Am/Pu in seawater, global fallout in recent soils
Protocol for 10-g Samples
Dissolution/Leaching
Dip
honi
x
HEDPAoxidation
Resins:• TRU• TEVA• UTEVA
tracers0.1M HCl-0.3M HF, AA
"Matrix"
0.5M HEDPA
H3PO4 + actinides, Ln’s
{oneor
more Sepa
rati
on Am, Pu, etc.• alpha spectrometry• ICP-MS
“Fenton’s Reagent”H2O2 + Fe2+ OH + OH- +Fe3+
Actinide Retention on Diphonix Resin
Diphonix Resin
•high retention of actinides, Ln•Low retention common ions•Tolerate to HF
Elution:HEDPA
Acid Dependency
Curves
Indicates that actinides should elute easily at
concentrations ~0.5M
0.5M HEDPA Elution Volume (mL)
0 5 10 15 20 25 30 35 40
Am
Re
cove
ry (
%)
0
20
40
60
80
100
Prior ResultIncremental
Elution of Am
Fenton’s Reagent Oxidation
finished
Treatment:
40 mL 0.5M HEDPA + 1 mL
HNO3 + 40 mL H2O2 + 0.17 g
Fe(NH4)2(SO4)26H2O
Temperature ~90oC
H2O2 + Fe2+ OH + OH- +Fe3+
Actinide Separations
TRUTRU
Resin
12
3 45
6
3
2
12.5M HNO3
2.5M HNO3/0.1M NaNO2
2.5M HNO3
9M HCl4M HCl
4M HCl/TiCl3 6
5
4
4M HCl2.5M HNO3
2.5M HNO3/0.1M NaNO2
2.5M HNO3
9M HCl1M HCl
0.1M Ammonium Bioxalate
12
3 45
6DiscardAm
Pu DiscardTh
U
Sample(3M HNO3, 0.7M Al(NO3)3, FS, AA)
Final clean-ups: Am/Ln on TEVA; U on UTEVA
TRUResin tolerates high PO4
10-g Samples: Yields
Am Pu Th U
Yie
ld (
%)
50
60
70
80
90
100 Samples (n=7):•3 EML soils•2 IAEA sediments•2 Fe-rich soils
10-gram samples were leached with
HNO3/HCl.
10-g Samples: Results
0.60 0.70 0.80 0.90 1.00 1.10
EML-9409
EML-9509
EML-9803
IAEA-300
IAEA-135
Activity Ratio: FSU/Standard
Am-241 Pu-239/240
Table 1: EML and IAEA intercomparison values.
Protocol for 50-g SamplesStep 10-gram* 50-gram
Leaching
70 mL each:6M HCl/8M HNO3
4 hrs., 90oC
150 mL each:6M HCl/8M HNO3
4 hrs., 90oC
Load Sol’n
Add HF (0.5M), AA, adjust pH=1
ppt Fe(OH)3
HCl, HF, AA, H2O to ~300 mL2M HCl – 0.5M HF
*Kim, Burnett, & Horwitz ( 2000)
Conditions - Diphonix
Step 10-gram 50-gram
DiphonixColumn
1.2-cm diameter10 mL resin
same13 mL resin
Elution 0.5M HEDPA35 mL
same40 mL
OxidHEDPA*
Fenton’s ReagentHNO3/H2O2/Fe2+
same
*Oxidation of HEDPA is done in a glass beaker on a hot plate – the reaction is complete in approx. 30 minutes
Conditions – Final
Step 10-gram 50-gram
TRUColumn
0.6-cm dia, 5 mL~15 mL HNO3-Al(NO3)3-FS-AA
0.6-cm dia, 6 mL~25 mL HNO3-Al(NO3)3-FS-AA
TEVA*(Am)
Thiocyanate separation
same
Source Prep
CeF3 microprecipitation
same*Am fraction purified of lanthanides on TEVA column to prevent
thick source; Pu is processed directly after TRU
Spike Tests (50-g Soil)
0 20 40 60 80 100
Source
TRU.Resin
HEDPA Oxid.
HEDPA Elution
Diphonix Adsorption
Fe(OH)3 ppt
Yield (%)
Am SCSPu EML-1Pu EML-2
Am-241 and Pu-239 spiked samples. Matrix = HNO3/HCl leach of 50-g soil and sediment
samples.
IAEA-300 (Baltic Sea Sediment)
•50-g sample, leached with 6M HCl/8M HNO3
•Run through entire procedure…
Analyte Yield%
FSUmBq/g
IAEAmBq/g*
Am-241 95 1.45±0.05
1.381.2-1.5
Pu-239/240 37 3.98±0.12
3.553.44-3.65
Pu-238 37 0.28±0.03
~0.15#
* recommended value/range
# information value only
EML Soil 0009:•50-g sample, leached with 6M HCl/8M HNO3
•Run through entire procedure…Analyte Yield
%FSUmBq/g
EMLmBq/g*
Am-241 100 6.8±0.2 1-100
Cm-244 100 124±3 ~100
Pu-239/240 49* 15.3±0.5 1-100
Pu-238 49* 17.3±0.6 --
*An additional 38% + ~15% recovered during 2nd and 3rd ppt; so total recovery through columns ~100%
Observations: 50-g Samples
•Solutions highly colored after HEDPA oxidation
•Load solution occasionally reacts with TRU.Resin – very strong oxidizing agent (CeIV?)
•Pu does not completely co-precipitate with CeF3 – hold-back effect?