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ll
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The distribution of radionuclides in 13 tissues of whole
tuna was determined by gamma-spectrum analyses of gill, bone,
skin including scales,
heart, pyloric caeca,
light muscle, dark muscle,
stomach,
stomach content,
intestinal content, gonad and kidney.
from 11 tuna
liver,
spleen,
intestine,
The samples were obtained
(7 skipjack, 2 yellowfin and 2
bigeye) that were
landed in Tokyo between June 12 and September 14.
tissues were not available from all fish.
All types of
The radioactivity of
seven gamma~-emitting nuclides by tissues is given in Table 4
without segregation for month of landing,
species or area.
Analysis for Fe?> requires special sample preparation and
detection equipment.
This radionuclide decays to stable man-
ganese-55 (Mn?>) by electron capture and, in the process, a
5.9 kilovolt X-ray is emmitted which is not detected by the
usual method of gamma-spectrum analysis.
energy of the radiation,
Because of the low
a thin sample with a minimum of self-
absorption is required for counting.
This is accomplished by
separating the iron isotopes from other transition elements in
the sample by selective elution of iron in its chloro-complex
form from an anion-exchange resin by the method of Kraus and
Moore (1953) as modified by Joyner and Chakravarti (1960).
X-rays emitted by the Fe?” in the sample were detected by a
thin (2 mm), beryllium-coated sodium iodide crystal.
The