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The simplest method of analysis is the direct solution of bone ash in HNO, dilution to
suitable volume, and determination of strontium content by flame photometry. The direct
analysis did not have sufficient sensitivity, so the separation of strontium from calcium was
made by a double nitrate precipitation. At the low concentrations of strontium found in bone
it was necessary to add barium as a carrier. This brought the recovery of strontium up to
over 90%.
The analytical procedure is as follows:
1. Ash the bone sample in a nickel crucible at 900°C.
2. Grind in a mortar to a fine powder.
3. Weigh out 5 grams into a 250 ml centrifuge bottle.
4. Add 44 ml of water and then slowly add 154 ml of 90% nitric acid to bring concentration
to 75% HNOs.
5. Add 20 mg of Ba++ carrier (as BaCl.) in the 2 ml of solution.
6. Stir rapidly for thirty minutes (mechanically).
7. Centrifuge for ten minutes at about 2000 r.p.m.
8. Decant and repeat steps 4 thru 7 at % the original volume.
9. Decant as much of the liquid as possible and transfer to a 100 ml beaker with water.
10. Evaporate to dryness and pick up with 10 ml of concentrated nitric acid.
11. Add 5 ml of 1000 ppm Lisolution, dilute to 100 ml and run flame photometry.
ae
D. Determination of elemental strontium in bone.
E. Determination of Sr~90 by separation and counting of Y-90:
1. After the sample on the brass holder has been counted for total strontium and has
reached equilibrium, it may be used for Y—90 separation.
2. Count the sample and record data.
3. Remove the sample from the brass holder. Wash the holder with about 25 ml of water.
Allow washings to fall into beaker with the bulk of the paper.
4. Bring to a boil and filter thru No. 41 paper into a 50 ml platinum dish. Wash the beaker
and paper with approximately 15 ml more of water.
5. Evaporate to dryness on a sand bath. Add approximately 20 ml of HF and evaporate to
dryness again.
;
6. Pick up the residue with approximately 5 drops of HCl. Transfer to a beaker with water.
Bring volume to about 50 ml. Add 10 mg of lanthanum carrier. (This carrier must have
7. Bring to a boil and adjust pH to 6-7. Allow to stand for about 15 minutes and filter
thru a 11%” glass fiber paper. Place on brass holder. Cover with Pliofilm and count.
8. Record time that filtration was completed. Count and record counting date and counting time.
9. Observe decay by counting at approximately 3-day intervals for a period of about 12 days.
The procedure was tested by measuring the recovery of Y-91 added to solutions containing
20 mg of Sr as the nitrate. The recoveries found with either paper or glass fiber filters were
94-99%.
< ere .
negligible beta activity.)
F. Measurement of activity:
Instrumentation for counting is similar to that used by Kulp (p. 30), except that it has no
anticoincidence circuit. The background counting rate is about 6 c.p.m.
Work on the developmentof a scintillation anticoincidence counter is in progress. This is
designed around a solution phosphor containing the active material in a volume of 5 to 10 ml.
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nom ARCHIVES