41
50 ml beaker) was analyzed for gamma radiation with a Radiation Instrument Development Laboratories Model 34-9, 400channel,
inch,
thick,
pulse height analyzer in conjunction with two 3x3-
thallium-activated,
sodium iodide crystals with 4-inch
copper and cadmium lined,
lead shielding.
Only that
portion of the gamma spectrum between 1.04 and 1.20 mev, which
contains the principal photopeak at 1.12 mev, was used for the
determination of the zn°?
gamma radiation levels in order to
reduce to a minimum interference from gamma energies of other
radioisotopes and from scattered Compton radiation.
ing period ranged from 200 to 1000 minutes,
The count~
depending upon the
activity of the sample and the instrument time available.
The
counts obtained were corrected for interference, background
and efficiency,
and expressed in disintegrations per minute to
facilitate comparison with data obtained under different
cir-
cumstances.
4.322 Stable zinc analyses.
reduce interference in the determinations,
(I) Separation.
To
zinc in the ashed
tissue samples was separated from the elements of the first
transition series of the periodic table by ion-exchange chroma~
tography.
The technique employed was a modification
(Joyner
and Chakravarti, 1960) of a method introduced by Kraus and Moore