MIL-DTL-11309J
4.5 Methods of inspection.
4.5.1 Tests on surface active material.
4.5.1.1 Iodine uptake. Weigh a sample of 2 grams of the LAS surface active material to
the nearest 0.005 gram on a piece of waxed paper. Transfer it to a 250-mL separatory funnel
(Corning No. 6340 or equivalent with stem cut to approximately 0.5 inch length) containing
50 mL of hot distilled water. Dilute to 75 mL with hot distilled water and swirl but do not shake
to dissolve. Add 2 mL of starch indicator solution and titrate with 0.1 normal (N) iodine solution
(12.692 grams iodine and 8 grams potassium iodide per liter of distilled water) until all sulfate is
destroyed as indicated by the appearance of the starch-iodine color. Swirl during the titration and
allow to stand with occasional swirling for 2 minutes after the initial appearance of the starch-
iodine color to be certain that the color does not fade.
4.5.1.1.1 Calculation. Calculate the result as follows:
Milligrams iodine = (126.92)(mL of iodine solution)(N)
(grams of sample)
4.5.1.2 Active ingredient. Weigh out 2 grams of LAS to the nearest 0.1 mg in a plastic
dish. Transfer to a 250-mL volumetric flask that is half full with distilled water. Mix well by
shaking and dilute to volume 250 mL with distilled water. Then mix again. Add 25 mL of
methylene blue indicator, 25 mL chloroform, 25 mL distilled water, and pipette a 25-mL aliquot
of LAS slowly into a 250-mL graduated cylinder. From a 50-mL burette, add as large a volume
as possible of 0.018 N hyamine 1622 without risk of over titrating. Stopper the graduated
cylinder and shake at least 30 times. To speed separation, hold the graduated cylinder in a
horizontal position until most of the chloroform has separated, then return the graduated cylinder
to the vertical position and swirl gently. After the mixture has separated, note color difference
between the two layers. Using the degree of color difference as a guide, continue adding
hyamine in successively smaller increments, shaking the graduated cylinder 30 times after each
addition. When colors are close, add the hyamine in 0.05-mL amounts until end point, at which
both will be aqua blue color. The end point is when the colors of the two layers match when the
graduated cylinder is observed at eye level against a white background. The comparison should
be made as soon as the layers separate completely.
4.5.1.2.1 Calculation. Calculate the result as follows:
Percent active ingredient = (mL hyamine)(N hyamine)(M.W.)(dilution)
(10)(sample weight)(aliquot)
Where:
N
=
Normality of hyamine solution (see sections 4.5.1.2.5 and 4.5.1.2.6)
M.W.
=
Molecular weight of LAS (=340)
Dilution
=
Volume LAS made to (250 mL) of LAS solution
Aliquot
=
Volume of LAS solution used for titration (25 mL)
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