MIL-DTL-87107E
APPENDIX A
from 0.1 to 0.5 microliters, is required for MS detectors. These syringes are routinely available from most
instrument manufacturers and chromatography supply houses.
A.4
REAGENTS AND MATERIALS
A.4.1 Stationary phase. The stationary phase should be one of the familiar non-polar
polysiloxanes, or equivalent. The following columns have been used successfully:
100% Dimethylpolysiloxane
(5%-Phenyl)-methylpolysiloxane
Either of the listed phases is satisfactory, provided baseline drift at high temperatures is maintained by
conditioning or by dual-column compensation.
A.4.2 Carrier gas. Either helium or nitrogen is suitable for FID detectors, although nitrogen is
known to give somewhat higher column efficiencies at lower flow rates, and is more economical. Helium
must be used with thermal conductivity detectors. Either helium or hydrogen may be used with a mass
spectrometer detector. The flow must be maintained constant to within one percent throughout the entire
range of operating temperatures by means of constant flow controllers.
A.4.3 Hydrogen. High purity, for flame ionization detectors.
A.4.4 Air. Dry, filtered, and oil-free, for flame ionization detectors.
A.4.5 Exo-tetrahydrodicyclopentadiene. Minimum ninety-nine weight percent purity, hereafter
referred to as C-10.
A.4.6 N-pentane, n-hexane, or petroleum ether. Chromatographic purity.
A.4.7 Qualitative calibration mixtures. A series of known hydrocarbons is used for calculating
column resolution. Prepare a mixture containing about one percent (by volume) each, in pentane or
hexane, of at least eight normal alkanes from highly pure (minimum 99 percent) samples which have
boiling points in the 70°C to 250°C range. The mixture must contain n-dodecane and n-tetradecane.
A.5
PREPARATION OF APPARATUS
A.5.1 Column. Any conventional method of conditioning and installing the column is
satisfactory, provided the system is free of gas leaks and the column resolution meets the minimum
requirement specified in A.5.2.
A.5.2 Column resolution. Run a sample of the qualitative calibration mixture and measure the
retention times and widths of the n-dodecane and n-tetradecane peaks as shown on Figure A1.
Resolution is defined as the difference in retention times for n-C12 and n-C14 divided by their average
width:
2 (RT14 - RT12 )
R=
W14 + W12
Resolution determined in this way must be at least 5.0 and can be optimized by varying the temperature
program and the carrier flow rate. If resolution cannot be increased to at least 5.0 by optimizing these
parameters, it is necessary to use a difference column.
A.5.3 Chromatograph. Place in service according to the manufacturer's specifications paying
particular attention to flow rates through the detector.
A.6
PROCEDURE
A.6.1 Suitable sample. Establish a suitable sample volume by making several trial runs with the
qualitative calibration mixture. For FID instruments, the volume may be between 0.5 and 1.0 µL. For
TCD instruments, volumes from 1.0 to 5.0 µL have been found satisfactory. For MS instruments,
volumes from 0.1 to 0.25 µL have been found satisfactory.
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