MIL-DTL-87173B(USAF)
APPENDIX A
A.6.4 Compute a response factor for MCH as described in A.7. Repeat the procedure at least three
times for each calibration sample and find the mean value for each response factor. Then dilute the PF-1
acceptance sample and run in the same way as the calibration standards, and determine its composition
as described in A.7.
NOTE 9. For MCH and C-10, extra peaks which are within plus or minus ten percent of the retention time
for MCH or C-10, respectively, shall be considered part of the MCH or C-10 peak areas. If commercial
grade MCH was used to blend the PF-1 acceptance sample, appreciable amounts of heptane and
toluene may appear as resolved peaks near the MCH peak. These peak areas should be added,
uncorrected, to the area of the MCH peak. Assuming unit relative response factors for these materials
does not seriously affect the accuracy of the method.
A.7 CALCULATIONS
A.7.1 C-10 is used in each case as an internal standard, and is considered to have a response factor of
1.000. After analysis with each calibration standard, group the peak areas which correspond to the MCH
and calculate the relative response for MCH by 70.2.
wt(MCH)
area (C-10)
K MCH =
X
wt(C-10)
area (MCH)
For each PF-1 acceptance sample, apply the calculated MCH response factor to each MCH peak area,
and sum the products to obtain a corrected MCH area. In the following equation, all hydrocarbons other
than those contained in the MCH and C-10 subgroups are considered impurities. A response factor of
1.000 is used for the impurities. Calculate the weight percent of each PF-1 component as follows:
K MCH A MCH
X 100
%MCH =
K MCH A MCH + A C-10 + A Impurities
A C-10
%C-10 =
X 100
K MCH A MCH + A C-10 + A Impurities
% Other hydrocarbons = 100 -(%MCH + % C-10)
.
A.8 PRECISION
A.8.1 Precision. Detailed precision studies have not been performed for this method. However, limited
results indicate the method is capable of the following precision.
A.8.2 Repeatability. Replicate analyses, performed under identical conditions in the same laboratory,
should yield results which do not vary more than one percent (absolute) from the mean value for each
component.
A.8.3 Reproducibility. When the same sample is analyzed in different laboratories according to this
method, the results for any component should not differ by more than 1.5 percent (absolute).
A.8.4 Accuracy. Back-analysis of a calibration standard should give results which agree with the
known values to within 0.5 percent (absolute).
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