BENZENE/TOLUENE IN GASOLINE BY GAS CHROMATOGRAPHY: ASTM D3606
(Equivalent Test IP 425)
EXPLANATION
Benzene is considered as a toxic material and the knowledge of its concentration can be an aid in evaluating the possible health hazards to persons handling and using the gasoline. This test method determines benzene and toluene in finished motor and aviation gasoline by gas chromatography. The range of determination includes benzene in 0.1 to 5 volume % and toluene in 2 to 20 volume % levels. The method has been tested in conventional as well as oxygenates containing gasolines. The method is not suitable for gasolines containing ethanol and methanol.

TEST SUMMARY
The sample is doped with an internal standard methyl ethyl ketone (MEK) and is then injected into a gas chromatograph equipped with two columns connected in series. The first column is packed with a nonpolar phase such as methyl silicone which separates the components according to their boiling points. The second column is packed with a highly polar phase such as 1,2,3-tris(cyanoethoxy) propane, which separates the aromatic and nonaromatic compounds. The eluted components are detected by a thermal conductivity detector and recorded on a strip chart. From the measured peak areas the concentration of each component is calculated with reference to the internal standard.

TEST PRECISION

Where X is the mean volume % of the component.

The bias of this test method is not known.