MIL-DTL-46225D
4.6.2.6.5 Solutions for acetate determination.
a. Iodine solution A. Dissolve 1.27 g of iodine and 1.6 g of potassium iodide in 100
mL of distilled water.
b. Iodine solution B. Dissolve 0.127 g of iodine and 0.16 g of potassium iodide in
100 mL distilled water.
c. Lanthanum nitrate solution. Dissolve 5 g of lanthanum nitrate in 100 mL of
distilled water.
d. Standard acetate solution. Dissolve 0.05 g of sodium acetate in 500 mL of
distilled water.
4.6.2.6.6 Acetate procedure. Add 1 mL of iodine solution A to the filtrate obtained in
4.6.2.6 and evaporate the solution to about 2 mL on a steam bath. Cool the solution and
quantitatively transfer it into a graduated test tube which has a one mL marking. Continue the
evaporation in the test tube until the volume has been reduced to 1 mL. Cool and add 3 drops of
iodine solution B, 3 drops of 5 percent lanthanum nitrate and 4 drops of 0.5 N ammonium
hydroxide in that order, shaking after each addition. Bring the solution to a boil, remove from
heat and allow it to stand for 10 minutes. Perform a comparative test starting with 25 mL of
standard sodium acetate solution using the procedure of adding iodine solution A, evaporation,
adding iodine solution B, evaporation, etc. The blue color produced by the test should be no
greater than that produced by the standard. Any color other than blue shall require a repeat of the
test procedure.
4.6.2.7 Lead carboxymethyl cellulose. (see 6.8.5 for precaution) Transfer 2.00 g of a
dried sample to a 250 mL beaker. Add 75 mL of glacial acetic acid to the beaker and place
beaker with contents on a steam bath, or moderately heated hot plate (do not let solution boil
down to dryness). Swirl gently for a few minutes. Allow the beaker to stand on the steam bath
covered with a watch glass for 30 minutes. While hot, filter through a tared sintered glass
crucible or a Gooch crucible fitted with 934AH filter mats or equivalent. Use an additional 50
mL of hot glacial acetic acid to rinse beaker and crucible. Treat residue in crucible with three 20
mL portions of cold 10 percent lead acetate solution, by filling the crucible with the lead acetate
solution and applying gentle suction. Wash thoroughly with hot (40-90 degrees C) distilled
water, then dry at 105 plus or minus 5 degrees C for 1 hour, cool in a desiccator and weigh.
Calculate the percentage of lead carboxymethyl cellulose as follows:
Percent lead carboxymethyl cellulose = (A-B) x 100/C
Where:
A = weight of crucible plus residue
B = weight of crucible
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