EXPLANATION
To reduce the ozone reactivity in toxicity of automotive evaporative and exhaust emissions regulations limiting the concentration of benzene and the total aromatic content of finished gasoline have been established. This test method can be used for this purpose. The method is also applicable to gasolines containing oxygenates such as alcohols and ethers as additives, since it has been found that they do not interfere with the analysis of benzene and other aromatics. Aromatics in the following concentration range can be determined: benzene 0.1 to 5; toluene 1 to 15; individual C8 aromatics 0.5 to 10; total C9 and heavier aromatics 5 to 30; and total aromatics 10 to 80 liquid volume %. The aromatic hydrocarbons are separated without interference from other hydrocarbons in the finished gasoline. For C8 and C9 and heavier aromatics some interference is expected from nonaromatic hydrocarbons.
TEST SUMMARY
A two column chromatographic system equipped with a column switching valve and a flame ionization detector is used. The sample is doped with an appropriate internal standard such as 2-hexanone. The flame ionization detector response, proportional to the concentration of each component, is used to calculate the amount of aromatics that are present with reference to the internal standard.
TEST PRECISION
Where range is in mass %, and X is mass %.