tower, Wash 3 times with 5 ml of absolute ethanol. Dry precipitate at
110°C for 10 min. Cool ina dessicator, Weigh as KC10,. Mount and
count.
Ad
SEPARATION OF CHLORINS ACTIVITY
Apparatus for chlorine determinations permitted the analyses of
three samples in duplicate in less than 60 min, The procedure for deter~
mining C138 ig given below,
Step 1. Transfer 3 ml of the gross activity to a 50-ml centri-
fuge tube. Add 3 drops of Fet? (20 mg/ml); 3 drops of BrO3 (20 mg/ml)
and 3 drops of 193 (20 mg/ml). Add concentrated NH,OH drop by drop
until the precipifate of Fe(OH), is formed, Add one drop in excess.
Centrifuge and decant the supernatant into a separatory funnel.
Step 2.
To the supernatant solution add NaHSO,
colorless solution is observed.
dropwise until a
Adjust solution to nf 2 with concentrated
HNO3,
;
Step 3. Add approximately 25 ml of 0.25 M TTA in CCl, to the
solution of Step 2. Pour the mixture through the side arm of the separae
tory funnel and stir for 2 min.
Step 4.
Separate the CCl, layer and wash aqueous fraction with
pure cCl,. Separate again. To the aqueous phase add an equal volume of
CCl, and while the mixture is being stirred add approximately 3 ml of
concentrated HNO3;. The characteristic yiolet color of iodine will then
form in the CCl, phase. Remove this layer and wash the aqueous phase
repeatedly with cCl, until the violet color is barely discernible, Then
add 5 drops of a saturated solution of Na.NO, and wash again with CCl).
Separate by removing the lower (organic) phase.
Step 5.
Stirring the aqueous phase add dropwise 0.1 M KMn0, until
a brown residual color is observed.
At this point
add NaNO.
drop by
drop until the aqueous phase becomes colorless. Extract with CCl, wmtil
no color is observed in the CCl, phase. Then do an additional
raction,
Step 6, Transfer the aqueous phase to a boiling flask which con-
tains 5 g oF crystalline KMn0, (see Note 1). Heat gently, The resultant
Clo-air mixture is bubbled through a solution of 0,1 M NaHS03,
Step7. aAcidify the NaHSO3 solution with concentrated HNO3.
AgNO solution in excess and precipitate AgCl.
Step8.
sda
Collect precipitate on a pre-weighed filter paper using
a small filter tower, Wash 3 times withsmall portion of acetone.
Mout precipitate on a planchet and count. After decay counting is
completed, heat the precipitate for 10 min at 110°C. Cool precipitate
in a dessicator and weigh to a constant reading,
A.4.1
Kotes
1.
The boiling flask is so constructed that when it is
attached to a Vigreux column and receiver, air my be drawn through the
system by aspiration.
138