10. Transfer the ground fused material to a 3-liter beaker containing 500 mi of hot distilled water, stirring constantly until the particles are dispersed.
11. Add slowly with continued stirring, 1000 ml of 60% HClO,.
This is sufficient to neutral-
ize the fused material and allow for an excess of acid.
12, Evaporate with mechanical stirring until dense white HClO, fumes are detected. The
silica is now dehydrated.
13. Dilute to 2.5 liters with distilled water and allow to settle.
14. Filter the silica on No. 5 Whatman paper with suction. Wash with 250-500 ml of hot
5% HCl, then with 250 ml of distilled water.
Transfer the filtrate and washings to the original
15. Remove the silica from the filter paper and dry in a 110°C oven overnight. Break up
the aggregated material with a mortar and pestle, then transfer to a 250 mi platinum dish.
16. Moisten the silica with 10% H.SO,, then add about 100 ml of HF.
17. Evaporate on a sand bath to SO, fumes to volatilize the silica. Cool and dilute with
distilled water, transferring the resulting solution to the original soil filtrate, and add 20 mg
Sr++ carrier.
18. Neutralize the filtrate with NaOH pellets until the pH is 44.5. At this point add slowly,
with stirring, 50 grams of Na.CO, and allow the precipitate to settle. Filter through No. 5
Whatman paper with suction and discard the filtrate.
19. When the precipitate is dry, remove from the filter paper and transfer to the original
beaker. Dissolve in 200 ml of concentrated HCl and evaporate slowly to dryness. Do not bake.
20. Now add 460 mlof distilled water and stir mechanically until the residue is completely
dispersed.
21. Add slowly, 1540 ml of 90% HNO, with continuous mechanical stirring and allow to remain stirring for 4% hour.
22. Allow to settle until the supernatantis clear, then decant as much 75% HNO,as possible.
23. Transfer the precipitate and remaining acid to a 250 ml centrifuge bottle, centrifuge and
OEATTNEG Sh. ee ke
Wash thesilica with 1% H.SO,, and discard the washings.
decant, discarding the supernatant.
24. Carry out another 75% HNO; separation using a volume of 200 ml.
25. At this point the bulk of the calcium should be removed leaving strontium nitrate and
insoluble material. Add 100 mi of hot distilled water to the precipitate, centrifuge and decant
into a 250 ml beaker.
26. Wash again with 50 mi of hot distilled water adding the supernatant liquid to the
beaker after centrifugation. The residue can now be discarded.
27. Evaporate the filtrate slowly to dryness.
28. Now carry out a final 75% HNO;separation in the 250 ml beaker. (100 ml volume)
29. Filter through a fluorothene funnel on a glass fiber filter. Transfer the funnel to a clean
filter flask and wash out the acid with anhydrous ethyl ether.
30. Place the filter on a brass disk and ring assembly (Tracerlab), cover with 0.001 inch
Pliofilm and beta count.
Recovery values for the above procedure are about 75%.
C. Separation of total radiostrontium from vegetation and foods:
1. Ash the sample in a nickel crucible at 900°C.
2. Estimate the amount of ash, add four times this weight of Na.CO, and fuse.
3. Dissolve, remove silica, and collect the strontium by carbonate precipitation as for soil.
4, Run a double nitrate precipitation as for bone using acid volumes of 200 ml for the first
precipitation and 50 ml for the second.
33
DOM ARCHIVES
rot
beaker.