MIL-DTL-3301D
W
Where: V = ml. of N/10 oxalic acid used
N = normality of oxalic acid
W = weight of original sample, gm.
Note: See 4.4.10.1 for alternate procedure for the analysis of Manganese.
4.4.10 Lead. Transfer the remaining 80 ml. portion of the solution obtained as described in paragraph
4.4.9 to a beaker and evaporate to 5 ml. Make the solution slightly alkaline with ammonium hydroxide.
Acidify with acetic acid and add an excess. Bring 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 = 80.1 A
W
Where: A = weight of residue, gm.
W = weight of original sample, gm.
4.4.10.1 Alternate procedure for the determination of lead and manganese by the
atomic absorption spectrophotometric method.
4.4.10.1.1 Specimen. The specimen shall consist of approximately 0.5 gm of the asphaltic compound
weighed to within 0.2 mg. in a 125 ml. flat bottom flask. Two specimens shall be prepared and
determined in duplicate.
4.4.10.1.2 Apparatus.
(a) Atomic absorption spectrophotometer
(b) Volumetric flasks, 50, 100 and 500 ml.
(c) Flat bottom flask, 125 ml with ground glass neck
(d) Condensers with ground glass fitting (suitable with 125 ml. flat bottom flasks)
(e) Ventilated steam bath
(f) . Hot plate in ventilated hood
(g) Pipettes, 1, 3, 5 and 8 ml.
4.4.10.1.3 Materials.
(a) Nitric acid, 70 percent
(b) Perchloric acid, 70 percent
8
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