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ASTM D7504-2018 pdf free download

ASTM D7504-2018 pdf free download.Standard Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and Effective Carbon Number
1. Scope
1.1 This test method covers the determination of total nonaromatic hydrocarbons and monocyclic aromatic hydrocar- bons in benzene, toluene, ethylbenzene, p-xylene, o-xylene, styrene and mixed xylenes by gas chromatography. The purity of benzene, toluene, ethylbenzene, p-xylene, o-xylene, styrene and mixed xylenes is also 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 The limit of detection (LOD) is 0.0002 wt % and limit ofquantitation (LOQ) is 0.0006 wt % for impurities in toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, benzene, and styrene. 1.3 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. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.6 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
5. Significance and Use
5.1 Determining the type and amount of hydrocarbon im- purities remaining from the manufacture of toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, benzene, and sty- rene 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 con- taining nine carbon atoms or more. 5.2 This method may not detect all components and there may be unknown components that would be assigned inappro- priate correction factors and thus, the results may not be absolute.
6. Interferences
6.1 The complete separation ofp-xylene from ethylbenzene, or ethylbenzene and m-xylene from p-xylene can be difficult when either ethylbenzene or p-xylene is analyzed, respectively. The separation can be considered adequate if the distance from the baseline to the valley between the two peaks is not greater than 50 % of the peak height of lower of the two peaks.
7. Apparatus
7.1 Chromatographic data system is required. 7.2 Columns—The choice of column is based on resolution requirements. Any column may be used that is capable of resolving all significant impurities from the major component. The column and conditions described in Table 1 have been used successfully and shall be used as a referee in cases of dispute.7.3 Gas Chromatograph—Any instrument having a flame ionization detector and a splitter injector suitable for use with a fused silica capillary column may be used, provided the system has sufficient sensitivity, linearity, and range to deter- mine 0.0001 wt %, while not exceeding the full scale of either the detector or the electronic integration for the major compo- nent. It shall have a split injection system that will not discriminate over the boiling range of the samples analyzed. The system should be capable of operating at conditions given in Table 1. 7.4 Injector—The specimen must be precisely and repeat- ably injected into the gas chromatograph. An automatic sample injection devise is highly recommended. 7.5 Syringe—chromatographic, capable ofdelivering appro- priate µL volumes.

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