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Significance and Use
5.1 Determining the type and amount of hydrocarbon impurities remaining from the manufacture of toluene, mixed xylenes, and p-xylenes 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.
5.2 Purity is commonly reported by subtracting the determined expected impurities from 100.00. However, a gas chromatographic analysis cannot determine absolute purity if unknown or undetected components are contained within the material being examined.
5.3 This test method is similar to Test Method D2360, however, interlaboratory testing has indicated a bias may exist between the two methods. Therefore the user is cautioned that the two methods may not give comparable results.
1.1 This test method covers the determination of the total nonaromatic hydrocarbons and trace monocyclic aromatic hydrocarbons in toluene, mixed xylenes, and p-xylene by gas chromatography. The purity of toluene, mixed xylenes, or p-xylene can also be calculated. Calibration of the gas chromatographic system is done by the external standard calibration technique. A similar test method, using the internal standard calibration technique, is Test Method D2360.
1.2.1 A small amount of benzene in mixed xylenes or p-xylenes may not be distinguished from the nonaromatics 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 C 10 aromatics) can be detected by this test method at individual concentrations ranging from 0.001 to 1.000 weight %.
1.4 In determining the conformance of the test results to applicable specifications, results shall be rounded off in accordance with the rounding-off method of Practice E29.
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. For specific hazard statement, see Section 9.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D841 Specification for Nitration Grade Toluene
D2360 Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography
D3437 Practice for Sampling and Handling Liquid Cyclic Products
D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D4790 Terminology of Aromatic Hydrocarbons and Related Chemicals
D5136 Specification for High Purity p-Xylene
D5211 Specification for Xylenes for p-Xylene Feedstock
D6526 Test Method for Analysis of Toluene by Capillary Column Gas Chromatography
D6563 Test Method for Benzene, Toluene, Xylene (BTX) Concentrates Analysis by Gas Chromatography
D6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E260 Practice for Packed Column Gas Chromatography
E355 Practice for Gas Chromatography Terms and Relationships
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs
ICS Number Code 71.040.50 (Physicochemical methods of analysis); 71.080.15 (Aromatic hydrocarbons)
UNSPSC Code 12352005(Aromatic or heterocyclic compounds)