DISCUSSION
An experiment was performed with a spike solution of 237pu, 241am, and 237Np
to determine the activity distribution in the fat and filtrate portions. The
results show less than 1% of the activity in the fat after the cold 6N HNO3
These results might be expected since the spike solution has not been
wash.
Four samples from an inhalation metabolism
through metabolism mechanics.
experiment for 24lam in tissues were analyzed to determine the 24lam content
of the fat portion.
method described.
The sample was dissolved, filtered, and ashed by the
The filtrate and fat portion were counted separately.
The
results are given in Table 1. In the four tests, the amount of 241am remaining
in the fat portion ranged from 0.1 to 0.4% of the sample activity. For most
applications, the small amount of 241!Am retained by the fat may be considered
To date, in our laboratory, we
negligible and the fat could be discarded.
have adopted a conservative approach and processed all fat portions and combined
them with the sample.
To determine the ability to analyze the dissolved sample and recover the 24 1am
activity, seven metabolism tissue samples containing 24lam were dissolved.
The dissolved samples were assayed for **!am in a standardized jar counting
geometry using a thin layer NaI (Tl) crystal as described by Major et al.,
(1974).
Aliquots, ranging in size from 0.01% to 5.0% of the dissolved sample,
were analyzed for 24am by the isotope dilution procedure previously reported
(Major et at., 1974).
Americium-243 tracer and alpha spectrometry are used.
The results (Table 2) show satisfactory recovery of 241am from solution of
various tissue types and activity levels, and there is no apparent bias within
the limits of the procedures used.
In summary, the described dissolution procedure for tissue samples using HF
and HNO3 appears to be satisfactory for its intended purpose.
Using this
procedure, samples of 250 grams can be completely solubilized in less than an
hour.
The advantages of this procedure are:
a.
Equipment requirements such as charring and ashing furnaces and exhaust
facilities are reduced.
b.
Ashing odors are reduced.
c.
Labor to tend ashing samples is reduced.
d.
Cost savings on laboratory ware and reagents is achieved.
The procedure is expected to be adaptable to the analysis of large, low-level
samples, such as autopsy samples.
280