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|  MIL-E-82756(OS)
a.
Prepare a standard curve (see step e) as follows: Weigh 25.0 0.2 mg of pure resorcinol
and dissolve in 100 mL of 5 percent sodium carbonate solution. Dilute with water to
exactly 250 mL and use as a stock solution to make the dilutions for the standard curve.
b.
Place 4, 6, 8, and 10 mL of the stock solution in 100 mL volumetric flasks and dilute to the
mark with water. These standards contain 0.4, 0.6, 0.8, and 1.0 mg resorcinol.
c.
Prepare a sodium carbonate solution for the reference cell by diluting 100 mL of 5 percent
sodium carbonate solution from step a to 250 mL with water, then further diluting 10 mL of
this solution to 100 mL with water.
d.
Before scanning, zero the instrument at 288 with the sodium carbonate reference solution
in both the reference cell and the sample cell. With the sodium carbonate reference solution
in the reference cell, scan each of the standards (from step b) in matched 1-cm silica cells
from 300 to 275 . Determine the maximum absorbance at about 288 .
e.
Plot each absorbance versus mg resorcinol. The best straight line through the four points is
the standard curve.
f.
Combine the sodium carbonate extraction above (see 4.6.1.1) and dilute to 250 mL in a
volumetric flask.
g.
Dilute a 15-mL aliquot of this solution with water to 100 mL, scan in the spectrophotometer
as described in step d above for the standard, and refer this figure to the standard curve to
obtain A, the milligrams of resorcinol per 100 mL of the final dilution of the sample.
h.
Calculate the percentage resorcinol in the sample as follows:
Α (250)
100
Ξ
Περχενταγ ε οφ ρεσ ρχινολ
ο
15 Ω
1000
where:
W = Weight of sample in grams
A = The milligrams of resorcinol per 100 mL of the final dilution of the sample
4.6.1.3 EC, MTN, and TEGDN. Evaporate the methylene chloride solution from the sodium
carbonate extractions in a stream of air until the methylene chloride is completely removed. Transfer the
residue to a 250-mL volumetric flask with acetic acid. Dilute to volume with acetic acid and save for the
tests in 4.6.1.3.1 and 4.6.1.3.2.
4.6.1.3.1 EC. Determine the EC content by volumetric bromination of a 50-mL aliquot of the above
acetic acid solution in accordance with MIL-STD-286, Method 202.2.3 for EC.
4.6.1.3.2 MTN and TEGDN. Transfer a 25-mL aliquot of the acetic acid solution to a nitroglycerin
reduction flask, and complete the nitrate ester determination in accordance with MIL-STD-286, Method
208.1.3. The esters are determined as a sum, and it is necessary to make an assumption as to the ratio of
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