EXPLANATION
The determination of compound types by mass spectrometry requires, in some instances, a preliminary separation of the petroleum sample into representative aromatics and nonaromatics fractions, such as in Test Methods ASTM D2425, ASTM D2786, and ASTM D3239. This test method provides a suitable separation technique for this application. This test method is suitable for hydrocarbon mixtures boiling between 232 and 538° C. Alternative procedures are provided for 2 or 10 g of hydrocarbon mixture. Some components may not be eluted from the chromatographic columns for some type of samples under the conditions used in this test.
Test Method ASTM D2007 is an alternative method of separating high-boiling oils into polar compounds, aromatics, and saturate fractions.
TEST SUMMARY
A sample is charged to the top of a glass chromatographic column packed with activated bauxite and silica gel. N-Pentane is used to elute the nonaromatics from the column. When all of them are eluted, the aromatic fraction is eluted with diethyl ether, chloroform, and ethyl alcohol. The solvents are completely removed by evaporation, the residues are weighed and calculated as the aromatics and nonaromatics fractions of the sample.
TEST PRECISION
The bias of this test method has not been determined.