MIL-PRF-87896A
4.5.2 Tetrafluoromethane, carbon dioxide, nitrous oxide, and sulfur hexafluoride.
Tetrafluoromethane (CF4), carbon dioxide (CO2), nitrous oxide (N2O) and sulfur hexafluoride (SF6) in the
propellant shall be determined by gas chromatography.
4.5.2.1 Instrument Parameters. The analyst may vary the column dimensions, carrier gas flow
rate, and temperatures to optimize the analysis.
Detector:
Thermal conductivity detector, discharge ionization detector, or a pulsed
discharged helium ionization detector.
Column:
Packing:
Super Q, 80/100 (or equivalent)
Length:
4.9 m (16 ft)
ID:
1.75 mm (1/16 in.)
OD:
3.2 mm (1/8 in.)
Column material:
stainless steel
Carrier Gas / Flow Rate:
Helium (MIL-PRF-27407) / 19 mL/min
Temperatures:
Detector:
100°C
Oven:
42°C
Gas sampling valve:
42°C
4.5.2.2 Calibration. Prepare a gaseous standard of helium containing at least 0.1% NF3 and the
components being analyzed in a concentration between one tenth and 10 times the specification limit or
of the predicted measurement in the propellant sample. Analysis of the calibration standard must show a
clear separation of each specified component from all other components and from NF3.
4.5.2.3 Procedure. Inject the calibration standard into the column using a gas-sampling valve.
Record the retention times and peak areas for each component. The order of elution is
tetrafluoromethane, nitrogen trifluoride, carbon dioxide, nitrous oxide, and sulfur hexafluoride. Inject the
propellant sample to be tested into the column in the same manner as the calibration standard. Record
the retention times and the peak areas. Repeat two times.
4.5.2.4 Calculation. Compare the average peak area of the calibration standard to that of the
nitrogen trifluoride sample being tested. Calculate the concentration of each component using the
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4.5.3 Oxygen + argon, nitrogen, and carbon monoxide. The concentration of oxygen+argon
(O2+Ar), nitrogen (N2), and carbon monoxide (CO) in the propellant shall be determined by gas
chromatography.
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