5.1 This test method is suitable for determining the concentrations of known impurities in finished benzene and for use as an integral quality control tool where benzene is either produced or used in a manufacturing procedure. It is generally applied to impurities such as nonaromatics containing nine carbons or less, toluene, C8 aromatics, and 1,4-dioxane.

5.2 Absolute purity cannot be determined if undetected impurities are present.

1.1 This test method covers the determination of normally occurring trace impurities in, and the purity of, finished benzene by gas chromatography with external calibration. A similar test method, using the internal standard technique of calibration is Test Method D4492.

1.2 This test method is applicable for nonaromatic hydrocarbon impurities at levels from 5 to 2000 mg/kg and for benzene purities of 99.80 weight % or higher.

1.3 This test method is applicable for aromatic impurities from 5 to 2000 mg/kg in benzene.

1.4 This test method has been found applicable to heteroatomic species such as 1,4-dioxane, from 10 to 2000 mg/kg in benzene.

1.5 The limit of detection for aromatic impurities is 0.9 mg/kg, 2.7 mg/kg for 1,4-dioxane and 1.1 mg/kg for methyl cyclohexane.

1.6 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.

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

1.8 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. For specific hazard statements, see Section 9.