MIL-DTL-98B
DPA Purity Analysis Gas Chromatograph Parameters
HP 6890 Series Gas Chromatograph or equivalent
Oven Temperature Program:
Oven Settings:
Temp
140 deg C
#
Rate(deg C/min) Final Temp (deg C) Final Time (min)
Initial Time
2.00 min
1
20.00
240
2.00
Maximum Temp 320 deg C
2
25.00
260
4.00
Equib Time
0.50 min
3
0.00
Off
Column Parameters
Inlet parameters:
Restek RTX-5 30 M x 320 µ m X 0.25
Mode
Split
Temp
250 deg C
µ m (or equiv.)
Pressure
15.6 psi
Flow
2.7 ml/min
Split ratio
75.0
Velocity
49 cm/sec
Split flow
201 ml/min
Mode
Constant Flow
Total flow
206 ml/min
Gas Type
He
Detector parameters (Flame Ionization)
Temp
275 deg C
H2 Flow
40.0 ml/min
Air Flow
400 ml/min
Mode
Constant Makeup
Makeup flow 30.0 ml/min
Makeup gas
N2
Figure 2. DPA purity analysis.
4.2.3 Insoluble material. Dissolve 25 gm. of the sample in 100 milliliters (mL.) of
benzene (specific gravity of 0.878 at 20 degrees/20 decrees C.) or ethyl ether (specific gravity
0.717 to 0.723 at 20 degrees/20 degrees C.). Filter through a tared filtering crucible and wash
thoroughly with the solvent. Dry the crucible for one hour at 100 degrees C., cool in a desiccator
and weigh. Calculate the insoluble matter to percent of the weight of sample.
4.2.4 Moisture. Dry 4 to 6 gm. of the powdered material in a weighing bottle about 4
centimeters diameter. Heat for 4 hours at 40 degrees C. uncorked, and calculate the loss in
weight to percent of the sample taken and observe as moisture.
4.2.4.1 Alternate moisture method by gas chromatography. Water in DPA is determined
using a gas chromatograph fitted with a polymer-packed column and a thermal conductivity
detector (or equivalent). The internal standard used in the analysis is 1000 ppm of methanol
(MeOH) in reagent grade acetonitrile (ACN). Approximately 500 ppm of water is added to the
internal standard. The water addition increases the sensitivity of the analysis. The actual
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