The grccedure used for iodin
‘solacion orior co neutron activation i3 2
modification or shat of Studier (1,9).
a filter, activated charcoal,
soil.
The soil sample to be srocessed may de
ton-exchange resin, animal parts, vegetation or
Freeze drving can se used as appropriate
ple orior to analvsis.
to remove moisture from the san-
The sample is spiked with a known amcunt of 125; for es-
timation of the overall procedure yield.
The iodine is separated by placing the
sample in a quartz combustion apparatus and igniting the sample at high temperature (up to 1000°C) in a stream of oxygen.
The off-gases are passed through a
small bed of activated charcoal that retains the iodine.
The iodine is further purified 5v Durning the original charcoal trap in oxvgen and trapping the released Lodine on several milligrams of activated charcoal.
The iodine is then removed from the charcoal dy heating the charcoal in
a vacuum system, trapping the iodine in a quartz tube at liquid nitrogen temperature,
.
\
.
as
gs
and sealing the tube to make a quartz irradiation ampoule.
-
The
125.
.
Tin
the ampoule is determined by gamma-ray spectromecry to estimate the pre-
irradiation processing vield.
Typical yields range from 90% to 100%.
Quartz ampoules containing the iodine separated from the samples are
irradiated with reactor neutrons for 8 to 24 hours.
containing g known ratios of
samples.
19
125,
127,
,
and
4
129
I are
Comparator standards
irradiated with each set of
The neutron capture reactions used for the iodine activation analysis
are:
12764 y}28;
127 a n,2n) 126.Tt
~
Buy,
25 min
8° .y
Tin
128,,
( L)
126
(2)
Xe