ASTM D7504-12

Determining the type and amount of hydrocarbon impurities remaining from the manufacture of toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, benzene, and styrene used as chemical intermediates and solvents is often required. This test method is suitable for setting specifications and for use as an internal quality control tool where these products are produced or are used. Typical impurities are: alkanes containing 1 to 10 carbons atoms, benzene, toluene, ethylbenzene (EB), xylenes, and aromatic hydrocarbons containing nine carbon atoms or more.

This method may not detect all components and there may be unknown components that would be assigned inappropriate response factors and thus, the results may not be absolute.

1.1 This test method covers the determination of the total nonaromatic hydrocarbons and trace monocyclic aromatic hydrocarbons in toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, benzene, and styrene by gas chromatography. The purity of toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, benzene, and stryene can also be calculated. Similar test methods, using the internal standard calibration technique and the external standard calibration technique, are Test Methods D2360, D3797, D4492, D5060, D5135, D5917, and D6563 respectively.

1.2 Total aliphatic hydrocarbons containing 1 through 10 carbon atoms (methane through decanes) can be detected by this test method at concentrations ranging from 0.0001 to 2.5000 weight %.

1.2.1 A small amount of benzene in toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, or styrene may not be distinguished from the non-aromatics and the concentrations are determined as a composite (see 6.1).

1.3 Monocyclic aromatic hydrocarbon impurities containing 6 through 10 carbon atoms (benzene through C₁₀ aromatics) can be detected by this test method at individual concentrations ranging from 0.0001 to 2.5000 weight %.

1.4 In determining the conformance of the test results using this method to applicable specifications, results shall be rounded off in accordance with the rounding-off method of Practice E29.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.