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CRER-1068
It has been shown that barium precipitates quantitatively
with, strontium from 72% nitric acid (3), though losses of barium
are greater than those of strontium in both a ferric hydroxide
scavenge and a carbonate precipitation (4).
Barium losses were
therefore measured in a separate experiment designed to establish
a correction factor.
The combined weight of the natural strontium and barium
present in a sample never exceeded 0.4% of the weight of the
carrier.
This introduced a negligible error in the strontium yield.
Strontium-87 (390 keV, ti 4 = 2.8 h) and barium-139
setntillation spectrometer.
After correcting for radiochemical
yield, counting losses, and background radiation, the strontium-87
activity in the sample was compared with that in the strontium
standard at a specific time.
In a similar manner the bartium-139
‘activity was determined after correcting for the superposition of
the barium-139 photopeak on the strontium-87 Compton recoil continuum.
The counting equipment consisted of a 3" x 3" sodium
lodide thallium-activated crystal in conjunction with a 100-channel
pulse height analyzer.
Calcium was determined gravimetrically by the precipitation of calcium oxalate after the removal of silica (1).
A
second oxalate precipitation was necessary because of the presence
of magnesium, which co-precipitated to some extent with the
calcium (5).
The method was checked for losses and purity of the
calcium oxalate precipitate by adding caleium-47 to the sample
and measuring the specific activity of calcium after rigorous
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(165 keV, t1 = 1.4 h) were counted simultaneously ona ¥