Rapid Determination of Np/Pu in
Water Samples by ICP-MSAN-1438
Summary of Method Plutonium and Neptunium are separated and concentrated from 200mL water samples.
Pu and Np are concentrated from the water sample using a calcium phosphate precipitation. Pu-Np are separated on
2mL cartridges of Eichrom TEVA and DGA resins. Pu-Np are measured by ICP-MS. Measured values for 239Pu, 242Pu,
and 237Np agreed to within 1-4% of reference values, while 237Np agreed to within 15%. Decontamination factors of >106
were achieved for Pu over U (238U-H can interfere with the measurement of 239Pu by ICP-MS). Sample preparation forbatches of 12 samples can be completed by a single operator in <4 hours.
Figure 1. Sample Preparation
Reagents
TEVA Resin, 2mL Cartridges (Eichrom TE-R50-S)
DGA Resin, Normal, 2mL Cartridges (Eichrom DN-R50-S)
Iron carrier (50mg/mL Fe, as ferric iron nitrate)
242Pu tracer
1.25M Ca(NO3)2
3.2M (NH4)2HPO4Deionized Water
2M Al(NO3)3
HNO3 (70%)
HCl (37%)
NH4OH
HF (49%) or NaF
NaNO2
Sulfamic Acid
Ascorbic Acid
Hydroxylamine Hydrochloride

Water Sample + 242Pu Tracer
Add 1mL 1.25M Ca(NO3)2 and3mL 3.2M (NH4)2HPO4. Mix well.
Heating to near boiling can improve
tracer/analyte equilibration.

Adjust to pH 9 with NH4OH.
Cool to room temperature.
Centrifuge 3500 rpm, 5 min.
Decant Supernate.
Dissolve precipitate in 8mL 6M HNO3
and 8mL 2M Al(NO3)3.

Equipment
Vacuum Box (Eichrom AR-24-BOX or AR-12-BOX)
Cartridge Reservoir, 20mL (Eichrom AR-200-RV20)
Inner Support Tubes-PE (Eichrom AR-1000-TUBE-PE)Yellow Outer Tips (Eichrom AR-1000-OT)
600mL Glass beakers
50mL and 250mL Centrifuge TubesCentrifuge
Hot Plate
Analytical Balance
Vacuum Pump
ICP-MS System

Figure 2. Actinide Separation on TEVA - DGA(8) Rinse TEVA with 5mL 3M HNO3.
Cool samples to room temp. Fix
valence by adding: (mix between steps) (9) Strip Np from TEVA with 14mL
0.25M HCl-0.005M HF-0.01M-0.5mL 1.5M sulfamic acid
Hydroxylamine hydrochloride.
-40uL 50mg/mL Fe carrier-1.5mL 1M ascorbic acid (Wait 3 min)(10) Rinse DGA with:-1mL 3.5M NaNO2-5mL 8M HNO3
(1) Precondition 2mL TEVA,-20mL 0.1M HNO3cartridges with 5mL 8M HNO3.
-10mL 0.05M HNO3.
TEVA(2) Load Sample.
(11) Strip Pu from DGA with 11mL(3) Rinse centrifuge tube
0.02M HCl-0.005M HF-0.01M
with 5mL 6M HNO3. Add
Hydroxylamine hydrochloride.
to TEVA.*(12) Measure 237Np and Pu by(4) Rinse cartridges with:
ICP-MS.
-30mL 3M HNO3-15mL 9M HCl (Th removal)(5) Add 2mL DGA cartridge
below TEVA.**(6) Strip Pu from TEVA onto
DGA with 15mL 3M HNO30.1M Ascorbic Acid-0.02M Fe2+.

TEVA

DGA(7) Separate TEVA and DGA.
* Adding 50uL of 30% H2O2 to 6M HNO3 tube rinse can help improve U decontamination.
** Adding a 1mL UTEVA cartridge between TEVA and DGA can provide additional uranium decontamination.

References
1) Sherrod L. Maxwell, Brian K. Culligan, Vernon D. Jones, Sheldon T. Nichols, Gary W. Noyes, “Rapid determinationof 237Np and Pu isotopes in water by ICP-MS and alpha spectrometry,” J. Radioanal. Nucl. Chem., 287(1), 223-230(2011).
2) Sherrod L. Maxwell, Brian K. Culligan, Vernon D. Jones, Sheldon T. Nichols, Gary W. Noyes, Maureen A. Bernard,“Rapid Determination of 237Np and Plutonium Isotopes by ICP-MS and Alpha Spectrometry,” Health Physics,
101(2), 180-186 (2011).
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