AN-1409

Rapid Determination of Sr in
Building Materials

Summary of Method Strontium is separated and concentrated from 1.5 gram samples of concrete or brick.
Samples are finely ground and fused in a zirconium crucible for 15 minutes at 600°C with 15 grams of sodiumhydroxide. The fusion cake is dissolved in water and strontium is concentrated and separated from the matrix using acalcium phosphate precipitate enhanced with iron. A secondary precipitation with calcium fluoride removes additional
matrix and decreases the volume of precipitate. The calcium fluoride precipitate is dissolved with nitric acid-boric acidaluminum nitrate to form the Sr Resin load solution. Strontium is separated from remaining matrix and potentiallyinterfering radionuclides using stacked 2mL and 1mL Sr Resin cartridges. Batches of 12-24 samples can be prepared
for analysis in less than 8 hours. Radiostrontium is measured by gas flow proportional counting or liquid scintillation
counting. Chemical yield of strontium is determined by gravimetric yield of stable strontium or ICP-AES measurement.
Reagents
Sr Resin, 2mL Cartridges (Eichrom SR-R50-S)
Sr Resin, 1mL Cartridges (Eichrom SR1ML-R50-S)
Nitric Acid (70%)
Hydrochloric Acid (37%)
Hydrofluoric Acid (49%) or Sodium Fluoride
Deionized Water
1.25M Ca(NO3)2
3.2M (NH4)2HPO4
2M Al(NO3)3
Iron Carrier (50mg/mL Fe, as ferric nitrate)
Strontium Carrier (10mg/mL)
90Sr standard
Oxalic acid
Boric acid
Sodium Hydroxide

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 250mL Centrifuge Tubes
Centrifuge
Cupped Stainless Steel Planchets (~5mL volume)
Gas Flow Proportional Counter
Muffle Furnace
Hot Plate
Analytical Balance
250mL Zirconium crucibles with zirconium lids
Vacuum Pump

Figure 1. Sample Preparation
1.5g finely ground sample in zirconium crucible
Add 4mg of Sr carrier.
Heat samples to dryness on hot plate.
Add 15g of NaOH.
Cover crucibles with zirconium lid and placein muffle furnace at 600°C for 15 minutes.
Carefully remove samples from furnaceand cool in fume hood.
Add 25-50mL of water and heat on hot
plate to dissolve fusion cake.
Transfer to a 250mL centrifuge tube. Rinse
crucible with water. Dilute to 150mL with water.
Add 2mL 1.25M Ca(NO3)3, 1mL 50mg/mL Fe,5mL 3.2M (NH4)2HPO4. Mix well.
Centrifuge 3500rpm. Decant supernate.
Dissolve precipitate in 50mL 1.5M HCl. Dilute to170mL with water. Add 22mL 49%HF. Mix. Cool in ice
bath 10min. Centrifuge 3500rpm. Decant supernate.
Dissolve precipitate in 5mL warm 3M HNO3-0.25M
Boric acid, 7mL 70% HNO3, and 7mL 2M Al(NO3)3.

Figure 2. Strontium Resin Separation (Optional 90Y Ingrowth)(1) Precondition Sr Resin with
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:**(Options for 89/90Sr Descrimination)(8) Evaporate samples to dryness
on tared cupped stainless steel
planchets.

When necessary to obtain 89Sr and90Sr data:(9) Rinse Sr sample vials with 2mL
0.05M HNO3. Transfer vial rinse toplanchets. Evaporate to dryness.

- 15 mL 8M HNO3
- 10mL 3M HNO3 - 0.05 oxalic acid- 10mL 8M HNO3(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 elutein Sr Resin load and can be counted
by liquid scintillation or gas flow proportional counting.

(6) Dispose of (1) to (5) as waste.
(7) Strip Sr with 20mL
0.05M HNO3 at1mL/min.

(a) Sr fraction from step (7) can betransferred to a liquid scintillation
vial. 89Sr can be measured by Cerenkov counting (without LSC cocktail).

(10) Weigh planchets on an
analytical balance to determine
gravimetric yield of stable Sr(NO3)2.

2mL + 1mL
Sr Resin
Cartridges(11) Measure radiostrontium insamples on low background gas
flow proportional counter.

References
1)“Rapid radiochemical method for total radiostrontium (Sr-90) in building materials for environmental remediation
following radiological incidents,” U.S. Environmental Protection Agency, National Analytical Radiation EnvironmentalLaboratory, EPA 402-R14-001.
2)“Rapid method for sodium hydroxide fusion of concrete and brick matrices prior to americium, plutonium, strontium,radium, and uranium analyses for environmental remediation following radiological incidents,”U.S. Environmental Protection Agency, National Analytical Radiation Environmental Laboratory, EPA 402-R-14-004.
1955 University Lane Lisle, IL 60532, USA+1 (630)963-0320

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