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Alternate method for EC, MTN, and TEGDN |
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|  MIL-E-82756(OS)
the MTN and TEGDN. This ratio is 23:2.5. The factor in the calculation, Section 5.14 of Method 208.1.3,
is 2.917.
4.6.1.4 Alternate method for EC, MTN, and TEGDN. Evaporate a sample, extracted with
methylene chloride as in 4.6.1.1, to near dryness and dilute to 3 mL with methylene chloride. Transfer
approximately 1 mL of the sample to a nuclear-magnetic-resonance (NMR) sample tube with an
eyedropper. Add tetramethylsilane as an internal reference. (Since this analysis is based on internal
standards, weighing is unnecessary.) Agitate the mixture in the tube well enough to assure homogeneity,
precondition to instrument operating temperature for approximately 10 minutes, and then transfer to the
probe. Screen the sample and integrate under the instrument conditions deemed best by the operator to
ensure high optimization. Suggested settings for Hitachi R20A Model NMR are as follows:
Sweep width
600 cycles per second
Sweep time
250 seconds
Time constant
0.1
4 x 103 Hz
H1 level
Scan sensitivity
4X1
Integral sensitivity
1
4.6.1.4.1 Calculations. The quantitative analysis is as given in table II.
4.6.1.5 AP. Dry the thimble and residue from the methylene chloride extraction above, place in a
clean soxhlet extraction unit, and extract with 150 mL of 90 percent ethyl alcohol for 6 hours. Transfer the
extract to a 250-mL volumetric flask and dilute to the mark with alcohol. Place a 25-mL aliquot of the
alcohol solution into a 250-mL beaker, add 30-mL dimethyl formamide and 5 drops of 0.2 percent thymol
blue indicator, and titrate with a 0.1 molar sodium methoxide solution to a blue color change. Take a color
change to last 5 seconds as the end point. Determine the AP equivalent of sodium methoxide solution by
weighing an approximately 300 mg sample of pure, dry AP to 0.2 mg. Place in a 250-mL beaker, add
25-mL of 95 percent ethyl alcohol, 30 mL of dimethyl formamide, and titrate with the sodium methoxide
solution as with the sample.
a.
Calculate the AP equivalent of the sodium methoxide solution as follows:
γ α ονιυ šερχηλ ρατε τακεν
ο
Εθ
Λ σ διυ ετηοξιδε σ λ τιον
ο
ου
b.
Calculate the percentage AP in the sample as follows:
Εθ Α
Περχενταγ ε α ονιυ šερχηλ ρατε
ο
Ω
where:
A = mL sodium methoxide solution required for titration of sample
W = Weight of sample in grams
8
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