EXPLANATION
This test method covers an analytical scheme using the mass spectrometer to determine the hydrocarbon types present in virgin middle distillates in the boiling range 204 to 343° C (400 to 650° F), 5 to 95 volume % as determined by Test Method ASTM D86. Eleven hydrocarbon types with average carbon number value of paraffins from C10 to C18 can be analyzed. If nonhydrocarbon types such as sulfur and nitrogen containing compounds are present to any larger extent they will interfere with the spectral peaks used for the hydrocarbon-type calculation.
TEST SUMMARY
Samples are separated into saturate and aromatic fractions by Test Method ASTM D2549, and each fraction is analyzed by mass spectrometry. The analysis is based on the summation of characteristic of mass fragments to determine the concentration of hydrocarbon types. The average carbon numbers of the hydrocarbon types are estimated from the spectral data. Calculations are made from the calibration data dependent upon the average carbon number of hydrocarbon type.
TEST PRECISION
Based on an interlaboratory study, the following precision was obtained.
The bias of this test method is not known.