Meaning and use

5.1 It is generally necessary to determine the type and amount of hydrocarbon impurities remaining in the manufacture of toluene, mixed xylene, paraxylene, o-xylene, ethylbenzene, benzene and styrene used as chemical intermediates and solvents. This test method is suitable for setting specifications and as an internal quality control tool for the production or use of these products. Typical impurities are: alkanes containing 1 to 10 carbon atoms, benzene, toluene, ethylbenzene (EB), xylene, and aromatics containing 9 or more carbon atoms.

5.2 This method may not detect all components, and there may be unknown components that will be assigned inappropriate correction factors, so the results may not be very good.

ASTM D7504-2018 Standard Test Method for Determination of Trace Impurities in Mono-Aromatic Hydrocarbons by Gas Chromatography and Effective Carbon Number

Step 1: Scope

1.1 The test method includes the determination of total non-aromatic and monocyclic aromatic hydrocarbons in benzene, toluene, ethylbenzene, p-xylene, o-xylene, styrene and mixed xylene by gas chromatography. The purities of benzene, toluene, ethylbenzene, p-xylene, o-xylene, styrene and mixed xylene were also calculated. Similar test methods using internal and external standard calibration techniques are test methods D2360, D3797, D4492, D5060, D5135, D5917 and D6563, respectively.

1.2 For impurities in toluene, mixed xylene, p-xylene, o-xylene, ethylbenzene, benzene and styrene, the limits of detection (LOD) are 0.0002wt % and the limits of quantification (LOQ) are 0.0006wt %.

1.3 When using this method to determine the consistency of test results with applicable specifications, the results should be rounded according to the rounding method of Practice E29.

ASTM D7504-2018 Standard Test Method for Determination of Trace Impurities in Mono-Aromatic Hydrocarbons by Gas Chromatography and Effective Carbon Number

1.4 Values expressed in SI units shall be regarded as standard values. No other units of measurement are included in this standard.

1.5 This standard is not intended to address all safety concerns (if any) associated with its use. It is the responsibility of users of this standard to establish appropriate safety, health and environmental practices and to determine the applicability of regulatory restrictions prior to use.

1.6 This international standard is based on internationally recognized standardization principles established in the “Decision on Principles for the Development of International Standards, Guidelines and Recommendations” issued by the WTO Committee on Technical Barriers to Trade (TBT).