Rapid Determination of 89/90Srin 5g Concrete Samples

AN-1605-10
Summary of Method Strontium is separated and concentrated from 5 gram concrete samples. Samples are finely
ground and fused in a zirconium crucible for 30 minutes at 600°C with 30 grams of sodium hydroxide. The fusion cakeis dissolved in water, and strontium is concentrated and separated from the matrix using a calcium phosphate
precipitate enhanced with iron. A secondary precipitation with calcium fluoride removes additional matrix (includingsilicates) and decreases the volume of precipitate. The calcium fluoride precipitate is dissolved with nitric acid-boric acid-aluminum nitrate to form the load solution. Analytes are separated from remaining matrix and potentially interfering
radionuclides using two stacked 2mL Sr Resin cartridges. Radiostrontium is measured by gas flow proportional counting
or liquid scintillation counting. Chemical yields of strontium are determined by gravimetric yield or by ICP-AES. Batchesof 12-24 samples can be prepared for analysis in less than 8 hours. For aged samples, where the shorter lived 89Sr (t1/2= 50.55 days) is unlikely to be present, 90Sr can be determined from the direct separation of its 90Y daughter from up to10g concrete samples, using Eichrom Application Note AN-1606.
Figure 1. Sample Preparation
5g finely ground sample in zirconium crucible
Reagents
Sr Resin, 2mL Cartridges (Eichrom SR-R50-S)
Strontium Carrier (10mg/mL)
Iron Carrier (50mg/mL Fe, as ferric nitrate)
90Sr standard
HF(49%)
30% H2O2
Nitric Acid (70%)
Hydrochloric Acid (37%)
Deionized Water
3.2M (NH4)2HPO4
1.25M Ca(NO3)2
2M Al(NO3)3Oxalic acid
Boric acid
Sodium Hydroxide

Add 6mg Sr carrier.
Heat samples to dryness on hot plate.
Add 30g of NaOH.
Cover crucibles with zirconium lid and placein muffle furnace at 600°C for 30 minutes.
Carefully remove samples from furnaceand cool in fume hood.

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)
50mL and 500mL Centrifuge Tubes
Cupped Stainless Steel Planchets (~5mL volume)
250mL Zirconium crucibles with zirconium lids
Centrifuge
Gas Flow Proportional Counter
Muffle Furnace
Hot Plate/Heat Lamp
Analytical BalanceVacuum Pump

Add 50-100mL of water and heat on
hot plate to dissolve fusion cake.
Transfer to a 500mL centrifuge tube. Rinse
crucible with water. Dilute to 450mL with water.
Cool to room temp. Add 50mg Fe. Mix.
Add 8.5mL 3.2M (NH4)2HPO4 . Mix.
Centrifuge 10min. Decant supernate.
Dissolve precipitate in 200mL 1.5M HCl. Add 50mL 0.01M
HCl and 15mL 49%HF. Mix. Cool in ice bath 10min.
Centrifuge 10min. Decant supernate.

Dissolve precipitate in 7mL 3M HNO3-0.25M Boric acid, 7mL conc.
HNO3, 7mL 8M HNO3 and 7mL 2M Al(NO3)3. Warm as needed.

Figure 2. Strontium Resin Separation (Optional 90Y Ingrowth)(1) Precondition 2x2mL Sr Resinwith 10mL 8M HNO3.
(2) Load sample at 1-2mL/min.
(3) Rinse sample tube with 5mL
8M HNO3.
(4) Add tube rinse to Sr Resin.
Elute at 1-2mL/min.
(5) Rinse Sr Resin sequentially with:

Gas Flow Proportional Counting:*(8) Evaporate samples to dryness
on tared cupped stainless steelplanchets.
(9) Rinse Sr sample vials with 2mL
0.05M HNO3. Transfer vial rinse toplanchets. Evaporate to dryness.

- 20 mL 8M HNO3
- 10mL 3M HNO3 - 0.05 oxalic acid- 10mL 8M HNO3
(6) Dispose of (1) to (5) as waste.
(7) Strip Sr with 20mL 0.05M HNO3
at 1mL/min.
2x 2mLSr Resin
Cartridges(10) Weigh planchets on an
analytical balance to determine
gravimetric yield of stable Sr(NO3)2.
(11) Measure radiostrontium insamples on low background gasflow proportional counter.

*(Options for 89/90Sr Discrimination)(a) Sr fraction from step (7) can betransferred to a liquid scintillation vial.
89Sr can be measured by Cerenkov
counting (no LSC cocktail). 89/90Sr
may then be measured after adding
liquid scintillation cocktail.
(b) Sr fraction from step (10) can be
dissolved in 10mL 8M HNO3 after >7days of 90Y ingrowth. 89/90Sr can beremoved on Sr Resin. 90Y will elute in
Sr Resin load and can be counted byliquid scintillation or gas flow
proportional counting.
(c) Sr fraction from step (10) can bedissolved in 10mL 8M HNO3 after >7days of 90Y ingrowth. 90Y can beremoved on DGA Resin. 89/90Sr will
elute in DGA Resin load. Additional
rinsing will remove remaining Sr. 90Y
can be eluted in 0.1M HCl andcounted by gas flow proportionalcounting or liquid scintillation(Cerenkov).

*Additional discussion of 89/90Sr separation and measurement options can be found in Eichrom Application Note
AN-1624-10.
Method Performance (5g gram Concrete, Sr Resin Method)
Sample
12
34AVG% Sr tracer
recovery
78.5
77.8
80.5
62.2
75 + 890

Sr Bq/greference
1.416
1.416
1.416
1.416

90

Sr Bq/gmeasured
1.51
1.35
1.42
1.49
1.44 + 0.07

% bias6.6-4.6
0.2
5.2

References
1) Maxwell, Culligan, Hutchinson, Utsey, Sudowe, McAlister, “Rapid Method to Determine 89/90Sr in Large Concrete
Samples,” J. Radioanal. Nucl. Chem. accepted (2016). DOI 10.1007/s10967‐016‐4787‐4
1955 University Lane Lisle, IL 60532, USA+1 (630)963-0320

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