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Elsevier Puclocing Compan.
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~ RADIOCHEMICAL DETERMINATION OF PLUTONIUMIN SEA WATER.
SEDIMENTS AND MARINE ORGANISMS
R KAI M. WONG*
Woods Hole Oceanographic Institution. Weods Hole. Muss. 02543 :U S.A.:
Eihtaal tortie iaittear
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La
Ee {Received 7th May 1971}
Various procedures are available for the determination of plutonium in
aqueous samples, sediments and biological organisms. However, none is really
adequate for low-level analysis because they have either low sensitivity or they are
cumbersome for analysis of large samples.
In sea water analysis, the ion-exchange method’ is suitable only for small
volumes(51 or fess) and consequently the sensitivity is low for fall-out plutonium: the
bismuth phosphate coprecipitation method~ requires separation at temperatures of
8C-100° which is impractical for processing samples of 50! or more: and the iron(II)
hydroxide method? used to coprecipitate plutonium from 50-200 | samples at room
temperature usually shows low recovery.
The procedure described in this paper is a modification of the iron(II}
hydroxide method to separate plutonium from sea water by coprecipitation with
iron(IT) hydroxide and the recovery is significantly improved.
Of the many procedures available for separation of plutonium in soil and
sediments*~* and in biological samples?” '?, those involving complete dissolution
usually give low sensitivity because only a small amount of sample can be processed
conveniently. The leaching method’, which is capable of treating kilogram amounts
of soil, is more suitable for low-level analysis. The leaching method. with nitric and
hydrochloric acids, has been compared with the sodium carbonate fusion and the
hydrofluoric-perchloric acid total dissolution methods!” and the results showed no
significant difference between methods of analysis for fall-out plutonium in several
types of soil samples. Therefore this method was adopted for sediment analysis:
it is also applicable to the analysis of biological samples after they have been dryashed.
EXPERIMENTAL
Reagents
&
All the reagents used were of reagent grade. All water was distilled and then
deionized on a Dowex-50 cation-exchange column.
Tron carrier solution. 50 mg Fe?* ml7! in 0.5 M hydrochloric acid.
Plutonium-236 tracer. Standardized, 2-3 d.p.m. mi~' in 1 M nitric acid. This
heed not be kept clean of *7®Th and other a-active daughters since the procedure
* Present address: Scripps Institution of Oceanography, La Jolla, Calif. 92037, U.S.A.
Anal. Chim. Acta, 56 (1971) 355-364
9004280
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