MIL-DTL-98B
4.2.2.1 Procedure for making the DPA purity control standard. To a 25 ml volumetric
flask add 0.250 grams each of reagent grade indole, acridine and quinoline. These components
are used to determine detection capability of the "lights" and "heavies" used in the % Purity
determination and calculation. Dilute to mark with acetonitrile (ACN) such that the stock
standard is equal to approximately 10,000 ppm of each impurity. Place a 4 oz bottle on a 2-place
balance and tare the balance. Add 5.00 grams of the DPA control (>99.8%). Tare the balance.
Add 70.00 grams of reagent grade acetonitrile. Add 50 µ l of stock standard. Shake to mix well.
This standard contains approximately 0.01% of each impurity. Pour into five ½ oz. bottles. Seal
and label each bottle.
4.2.2.2 Method for determination of DPA % purity. Run a control standard by injecting
0.5 µ l of the control and integrating. The DPA analysis must be in statistical control prior to
proceeding. Place a solid sample of the test material in an 116o C convection oven to melt. Dilute
1.0 gram of the molten sample with 14.0 grams of reagent grade ACN. Inject 0.5 µ L of the
diluted sample into a gas chromatograph fitted with a split/spitless capillary inlet and a flame
ionization detector. Start the integrator. Report %Purity, %Lights, and %Heavies. DPA purity
input parameters shall be in accordance with Figure 2.
% Purity = % Total area-(% Lights + % Heavies)
Where: %Lights = total area% between solvent and DPA peak
or
Area counts between Solvent and DPA 100
Total Area Solvent Area
% Heavies = total area% after DPA peak
or
Area counts after DPA p eak 100
Total Area Solvent Area
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