-15-
lusteroid test tubes.
Oxalate fractions
The oxalate fraction of the primary ion-exchange separation of
sample P-6 was dried and redissolved in
concentrated HCl for
separa of the transition elements, as described by Kraus
6
Moore.
the
and
The sample was passed through a 0. 28 em2 x 26-cm column
containing Dowex-1-(200-400 mesh).
Determination of strontium-90
Samples of plankton and a sample of shrimp were analyzed for gr99
by the ion-exchange method of Kawabata and Held.
The ashed sample
was first treated with 80 per cent HNO3 to remove strontium from
the
bulk of the sample and from most of the other radioisotopes present.
The solution containing the strontium nitrate precipitate was filtered
through a glass filter and was then dissolved in hot 0.2N HCl.
After
cooling, it was passed through a cationic resin column and possible
contaminants were eluted from the column with 0.5 per cent oxalic
acid and 5 per cent ammonium citrate at pH 3.5.
The column was then
stored for 14 days to allow the ¥29 daughter to build up.
The Y99 was
reeluted from the column with ammonium citrate at pH 3.5 and
the
amount of Sr9° present was calculated from the amount of ¥99 recovered.
The identity of ¥99 was confirmed by determining the decay rate of the
sample eluted.