e. Procedure for determination of Sr~90 in plants:
1. Leach sample with twice its volume of 50% HCl solution with stirring for five minutes.
2. Filter.
3. Filtrate is then treated exactly as the soil leach, steps 6 through 11 on page 28. Where
insufficient calcium is present for good CaCO, precipitation, a weighed amount of SrCl.’6 H,O
may be added as carrier in step 6.
4. Solid plant material in the filter is burned to ash and also treated exactly as thesoil.
esrege
9. Dissolve precipitate in 50% HCl solution and repeat steps 6 through 8 until a constant
weight is obtained.
10. Store as solid CaCO;, ready for carbonate milking procedure.
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APICESSATE aa
7. Filter and check filtrate for completeness of precipitation by addition of Na,CO,solution.
8. Dry and weigh precipitate.
5. Samples should be stored separately as carbonates, ready for milking.
f. Milking procedure for carbonate samples:
1. Dissolve sample in 50% HCl, keeping volume as small as: possible.
2. Add dead yttrium carrier.
3. Add concentrated NH,OH to precipitate yttrium hydroxide completely.
NH,OH.
Add excess
Remove andstore filtrate for later milkings.
With a clean beaker in thefiltrator, and the vac.off, fill funnel containing the precipitate
with dilute (about 10%) HCl solution.
Allow to stand for a minute or two to dissolve the pre-
cipitate and then turn on the vac. collecting the solution in the clean beaker.
9. Wash paper with small amount of dilute HCl solution. Discard paper. ,
10. Add concentrated NH,OH dropwiseto filtrate until first signs of precipitate appear.
11. Add concentrated HCl dropwise to beaker with stirring to just dissolve precipitate. One
or two drops should suffice,
12. Add concentrated oxalic acid to solution in excess. White precipitate should quickly
appear.
13. Digest with heating for about ten minutes.
14. Filter in Fisher Filtrator using steel Tracerlab precipitation funnel and Whatman +42
1144” diameter paper. If filtrate is clear it may be discarded.
15. Dry precipitate by allowing vacuum to pull on it for about 5 minutes.
16. Carefully remove paper with sample and place on Tracerlab brass disk.
17. Cover with pliofilm and secure with brass ring.
18. Note sample number on bottom of brass disk.
g. Milking procedure for phosphate samples:
cata
Filter in Fisher Filtrator, using Whatman #41 or 42 filter paper. Record timeof filtration.
Wash solid with dilute NH,OH solution. Use small amount, to keep volumeoffiltrate
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4. Digest with heating for abodt ten minutes.
1. Dissolve weighed amount of stored sample in as small volume of concentrated HCl as
Heating facilitates solution.
2. Add dead yttrium carrier.
3. Precipitate phosphate of yttrium by addition of 2 N NH,OH. Heating and vigorousstirring materially help obtain a clean precipitate. pH should not exceed 1.5 at any point in this
procedure.
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