-7In selected experiments, the rare earth fractions (ammo-
nium citrate, PH 3.5 a-d) were combined, evaporated to dryness,
ashed and redissolved in 0.2N HCl for separation of the individual rare earth elements by secondary elution according to
the method of Kimura et al. (1956).
Ten ml of a 1:1 suspension
- were hb
vVLLOOte
d
T-
5~56 used a8 carrier
of Dowex 50 in the H-form (0.2N HCl) were added to the rare
earth fraction in a beaker and stirred several times.
A ‘mother
colwm" of Dowex 50 resin was prepared as described above and
converted to the NH,TT*-form by passing NH, citrate, pH 2.5,
through the column, until the eluate was at pH 2.5.
The rare
earth resin suspension was added to the column and ammonium
citrate solutions of pH 2.8, 2.9 and 3.1 were passed through
until the rare earth fraction started moving down the column
as determined by a survey meter,
Ammonium citrate solutions
of pH 3.1 (120 mi), 3.3 (360 m1), and 3.4 (300 m1) were added
to elute the individual rare earth elements.
In other selected experiments pH 3.5 and/or 4.1 fractions
were reeluted from ion exchange columns containing Dowex 1*, an
anionic type resin (supplied in the chloride form), to separate
Mn, Co, and Zn from each other according to the method of Kraus
and Moore (1953).
These fractions were dried, ashed, and redis-
solved in 3-5 ml of concentrated HCl and added to a column of
6 mm diameter and 260 mm length.
The resin of 100-200 mesh was
prepared in the following manner.
The resin was twice soaked in distilled water in a beaker
and the solution containing the small particles was decanted.
* Dow Chemical Co., Midland, Michigan