ewe
WCLASSIFTED
ANALTTICAL DEVELOPMENT IN PROGRESS
The Instruments Brarmh of the Health and Safety Laboratory hasi been
developing a scintillation anti-coincidence counter for low larel
bets measurements. This is designed around a solution phosphar con
taining the active material in a volume of 5 to 10 ml. The prpble
has been worked on by three groups; the 4nelytical Branch devdloping
the method of obtaining the active material in solution, Profdssor
Kallaann of NTU working on the development of the optimum phosphor,
and the Instruments Branch working on the developat of ins
pontation..
The chemical operations were largely devoted to the separation
of
T°? from the rediostrontius plue strontium carrier obtained if our
normpal chemical procedures.
It was desirable to extract the
[*
into an organic solvent that would also be a suitable solvent] for
the fluors; such as terphenyl and the substituted anthracene.
Initial experiments showed that certain complexing agents
whifh
gave organic soluble compounds with Y also acted
the phosphor.
as quenchew
This was true of TIA (thenoyl trifluorcacetong).
for
Other reagents such as oxine gave poor extraction coefficients.
Tributyl phosphate (TBP) has been used in the extraction of
e
due to the presence of nitric acid which also extracts into
Br’ »
earths from very strong nitric acid solution. The resultingforganic
layers, however, were found to show very great quenching.
is is
It was not possible to wash out the HNO,, as the Tf activity
removed in the process.
oy
Extracting YT from saturated ammonium nitrate solutions with
s also
PEP
gave an organic layer which could be prepared as a good liquid
phosphor.
The pulse heights obtained are equivalent to phosphors
prepared directly from TBP. Both 75% and 3% satureted amnariim
mitrate solutions alse gave good extrection results, allow
easier manipulation than if completely saturated.
This technique should allow the ready messurement of very lw
levels
of Y°° ag carrier~free isotope, since the background of suc a scintéillation counter could be maintained at a low:level. This|proecedure may also be used for determination of Ce*** which is ong of the
known non-fractionating fission products present in aged fallout
debris. The second development is the use of a comparatives logarithmic absorption plot for isotope identification. In this pfethod,
the logarithm of the relative activity of the unknown with Parious
aluminum absorbers is plotted against the logarithm of the relative
activity of a known isotape such as P**.
The slope of the [resulting
ert G 7
UNCLASSIFI=D
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