MIL-DTL-82604A (OS)
4.5.1.2 Lead. Transfer the remaining 80-ml portion of the solution obtained as described in
4.5.1.1 to a beaker and evaporate to 5 ml. Make the solution slightly alkaline with ammonium
hydroxide. Acidify with acetic acid and add an excess. Heat to the boiling point and add
10 to 15 ml of a 10 percent solution of sodium or potassium dichromate. Boil the solution and
allow to stand for 16 hours. Note if lead is present as indicated by a yellow precipitate. If lead is
present, filter the solution through a tared Gooch crucible (or equivalent) and wash the
precipitate with water and alcohol. Dry the crucible and contents at approximately 110 ºC
(230 ºF) for 1 hour, cool, and weigh. Calculate the increase in weight of the crucible as lead in
the sample as follows:
Percent lead = 64.1A
W
Where:
A = weight of residue, g
W = weight of original sample, g.
4.5.1.3 Acidity or alkalinity. Dissolve a 5-g sample of the compound in 10 ml of toluene,
neutral to phenolphthalein. Shake the solution with 100 ml of distilled water in a 250 ml
separatory funnel for at least 5 minutes. Filter and titrate water phase with N /100 H2SO4 or
N /100 NaOH as necessary using phenolphthalein as indicator. Run a blank on an equal
volume of the water used.
4.5.1.4 Insoluble matter in CCL4.
4.5.1.4.1 Apparatus. The extraction apparatus shall consist of a heat resistant glass assay
flask, a block tin condensing coil with a nickel, copper, or tin-plated metal cap that fits securely
around the rim of the flask, and a glass siphon cup which is suspended under the condenser.
This apparatus shall be suitable for use with an electric hotplate or steam bath.
4.5.1.4.2 Method. Transfer a sample of approximately 6 g, weighed accurately to 0.1 mg,
into a tared stainless steel 200-mesh thimble. Fabricate thimble from a 15-centimeter (cm)
diameter circle of wire mesh by using the lower portion of a test tube as a form for folding the
thimble. This form should be of a diameter that just will fit into the glass siphon tube. Place
thimble containing the sample into the siphon cup. Do not allow the thimble to extend beyond
the top of the cup. Suspend the cup under the condenser by a fine wire bail. Add
approximately 60 ml of carbon tetrachloride to the sample in the cups and allow the excess
solvent to siphon over into the flask. Put condenser in place and circulate cold water through it.
Heat the flask on a steam bath or an electric hotplate. Allow the solvent to drip from the top of
the condenser at a slow to medium rate. Discontinue the extraction when the solvent drops
colorless from the siphon cup. Wash down the steel mesh with a fine jet of solvent from a wash
bottle. If the washings show any color, put the sample back into the siphon cup and continue
the extraction until the solvent again becomes colorless. Remove the steel mesh thimble
containing the residue, dry for 1 hour at approximately 100 ºC, cool, and weigh. Calculate the
percent insoluble in the solvent as fo1lows:
Percent insoluble in carbon tetrachloride = A B X 100
W
Where:
A = weight of steel mesh thimble plus residue after extraction, g
B = weight of steel thimble, g
C = weight of sample, g.
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