EIOLOGTCAL AND ENVIRONMENTAL STANDARDS FOR QUALITY CONTROL
Quality control of iodine activation analysis requires the use of standard
materials similar to the sample materials analyzed.
Such standard materials are
neeced to check the total procedure from iodine separation to final measurements.
The materials should be homogeneous, easy to store, and available in
quancity over a period of vears.
Several diological and environmental standard samples were odtained from
NBS and IAEA.
These included orchard ieaves (NBS-SRM-1571),
river sediment
(NFS-SRM~-4350), clam (LAEA-MA-3-1), human blood serum (IAEA~4-5), and wheat
flour (IAEA-V-5).
Also, grass collected from the Hanford Reservation was dried
and mixed for use as a standard.
Replicate iodine activation analyses were nade
on these materials, for which preliminary results are summarized in Table III.
e
aijct
vals (SD «
—
The values are given as means of replicate measurements 295% conridence inter-
v
.
as
127
1
The natural iodine (
I) measurements on these samples
were efound to
agree with the assigned values to within measurement uncertainties.
Larger
uncertainties were observed for the concentration values than for the isotopic
ratio values, as expected from an evaluation of the error sources in the oroce-
dure,
Additional replicate analvses are expected to reduce the uncertainties.