EXPLANATION
A knowledge of the amount of aromatics in gasoline is helpful in assessing the product quality and in evaluating the health hazard to persons handling and using gasoline. This test method determines benzene, toluene, C8, C9, and heavier aromatics, and total aromatics in finished motor gasoline and gasoline blending components. It has not been determined whether this method is applicable to gasolines containing oxygenates such as ethers and alcohols. Following concentration ranges, in liquid volume percent, can be determined by this test method:
Benzene 0.1 to 5; toluene 1 to 20; C8 3 to 25; C9 and heavier 5 to 30; and total aromatics 10 to 80.
TEST SUMMARY
A two column chromatographic system connected to a dual filament thermal conductivity detector (or two single filament detectors) is used. Sample is injected into the column containing a polar liquid phase. The nonaromatics are directed to the reference side of the detector and vented to the atmosphere as they elute. The column is backflushed immediately before the elution of benzene, and the aromatic portion is directed into the second column containing a nonpolar liquid phase. The aromatic components elute in the order of their boiling points and are detected on the analytical side of the detector. Immediately after the C8 aromatics have eluted, the flow through the nonpolar column is reversed to backflush the C9 and heavier aromatics from the column through the detector. Quantitation is done from the measured areas of the recorded aromatic peaks by utilizing factors obtained from the analysis of a blend of known aromatic content.
TEST PRECISION
Where X is the measured value.