1、Designation: D7504 17aD7504 18Standard Test Method forTrace Impurities in Monocyclic Aromatic Hydrocarbons byGas Chromatography and Effective Carbon Number1This standard is issued under the fixed designation D7504; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of total nonaromatic hydrocarbo
3、ns and monocyclic aromatic hydrocarbons inbenzene, 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 internalstanda
4、rd 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 of quantitation (LOQ) is 0.0006 wt % for impurities in toluene, mixedxylenes, p-xylene,
5、 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 roundedoff in accordance with the rounding-off method of Practice E29.1.4 The values stated in SI units are to be regarded as standard
6、. 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 responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practi
7、ces and determine theapplicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Reco
8、mmendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D841 Specification for Nitration Grade TolueneD1555M Test Method for Calculation of Volume and Weight of Industrial Aromatic Hydrocarbons and Cyclohexane MetricD23
9、60 Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography (Withdrawn 2016)3D3437 Practice for Sampling and Handling Liquid Cyclic ProductsD3797 Test Method for Analysis of o-Xylene by Gas Chromatography (Withdrawn 2014)3D4492 Test Method for Analysis of Benzene by
10、 Gas Chromatography (Withdrawn 2018)3D4790 Terminology of Aromatic Hydrocarbons and Related ChemicalsD5060 Test Method for Determining Impurities in High-Purity Ethylbenzene by Gas ChromatographyD5135 Test Method for Analysis of Styrene by Capillary Gas ChromatographyD5136 Specification for High Pur
11、ity p-XyleneD5211 Specification for Xylenes for p-Xylene FeedstockD5917 Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and ExternalCalibrationD6229 Test Method for Trace Benzene in Hydrocarbon Solvents by Capillary Gas ChromatographyD6563 Test Method for B
12、enzene, Toluene, Xylene (BTX) Concentrates Analysis by Gas Chromatography (Withdrawn 2018)31 This test method is under the jurisdiction of ASTM Committee D16 on Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsibility ofSubcommittee D16.01 on Benzene, Toluene, Xylenes,
13、Cyclohexane and Their Derivatives.Current edition approved June 1, 2017Feb. 1, 2018. Published June 2017March 2018. Originally approved in 2009. Last previous edition approved in 2017 asD7504 17.D7504 17a. DOI: 10.1520/D7504-17a.10.1520/D7504-18.2 For referencedASTM standards, visit theASTM website,
14、 www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM
15、standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all
16、cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D6809 Guide
17、for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related MaterialsE29 Practice for Using Significant Digits in Test Data to Determine Conformance with SpecificationsE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE260 Practice for Packed Co
18、lumn Gas ChromatographyE355 Practice for Gas Chromatography Terms and RelationshipsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs2.2 Other Document:OSHA R
19、egulations, 29 CFR paragraphs 1910.1000 and 1910.1200 43. Terminology3.1 See Terminology D4790 for definitions of terms used in this test method.4. Summary of Test Method4.1 The specimen to be analyzed is injected into a gas chromatograph equipped with a flame ionization detector (FID) and acapillar
20、y column. The peak area of each component is measured and adjusted using effective carbon number (ECN)5 correctionfactors. The concentration of each component is calculated based on its relative percentages of total adjusted peak area andnormalized to 100.0000 %.5. Significance and Use5.1 Determinin
21、g 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 testmethod is suitable for setting specifications and for use as an inte
22、rnal quality control tool where these products are produced orare used. Typical impurities are: alkanes containing 1 to 10 carbons atoms, benzene, toluene, ethylbenzene (EB), xylenes, andaromatic hydrocarbons containing nine carbon atoms or more.5.2 This method may not detect all components and ther
23、e may be unknown components that would be assigned inappropriatecorrection factors and thus, the results may not be absolute.6. Interferences6.1 The complete separation of p-xylene from ethylbenzene, or ethylbenzene and m-xylene from p-xylene can be difficult wheneither ethylbenzene or p-xylene is a
24、nalyzed, respectively. The separation can be considered adequate if the distance from thebaseline to the valley between the two peaks is not greater than 50 % of the peak height of lower of the two peaks.4 Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St.
25、, NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.5 Scanlon, J. T. and Willis, D. E., “Calculation of Flame Ionization Detector Relative Response Factors Using the Effective Carbon Number Concept,” Journal ofChromatographic Science, Vol. 23, August 1985, pp. 333339.TABLE 1 Recomme
26、nded Method ParametersInlet SplitTemperature, C 270Column:Tubing fused silicaLength, m 60Internal diameter, mm 0.32Stationary phase crosslinked polyethyleneglycolFilm thickness, m 0.25Column temperature programInitial temperature, C 60Initial time, min 10Programming rate, C/min 5Final, C 150Time 2,
27、min 10Carrier gas helium or hydrogenLinear velocity, cm/s at 145C 20 helium or 45 hydrogenSplit ratio 100:1Sample size, L 0.6Detector: flame ionizationTemperature, C 300Analysis time, min 38D7504 1827. Apparatus7.1 Chromatographic data system is required.7.2 ColumnsThe choice of column is based on r
28、esolution requirements.Any column may be used that is capable of resolvingall significant impurities from the major component. The column and conditions described in Table 1 have been used successfullyand shall be used as a referee in cases of dispute.7.3 Gas ChromatographAny instrument having a fla
29、me ionization detector and a splitter injector suitable for use with a fusedsilica capillary column may be used, provided the system has sufficient sensitivity, linearity, and range to determine 0.0001 wt %,while not exceeding the full scale of either the detector or the electronic integration for t
30、he major component. It shall have a splitinjection system that will not discriminate over the boiling range of the samples analyzed. The system should be capable ofoperating at conditions given in Table 1.7.4 InjectorThe specimen must be precisely and repeatably injected into the gas chromatograph.
31、An automatic sampleinjection devise is highly recommended.7.5 Syringechromatographic, capable of delivering appropriate L volumes.8. Reagents and Materials8.1 Purity of ReagentReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall confor
32、m to the specifications of the Committee on Analytical Reagents of the American Chemical Society,6 wheresuch specifications are available. Reagents with an establish purity greater than ACS reagent grade may be used.8.2 Carrier Gas, Makeup Gas and Detector Gases 99.999 % Pure. Oxygen in carrier gas
33、less than 1 ppm, less than 0.5 ppmis preferred. Purify carrier, makeup and detector gases to remove oxygen, water, and hydrocarbons.8.3 Air for the FID should contain less than 0.1 ppm total hydrocarbon.8.4 Equipment Set-up Check Sample8.4.1 High Purity p-Xylenep-xylene (99.99 wt.% or greater purity
34、)Most p-xylene is available commercially at a purity lessthan 99.9 wt. %, but can be purified by recrystallization. To prepare 2 qt.L of high-purity p-xylene, begin with approximately 1gal4 L of reagent-grade p-xylene and cool in an explosion-proof freezer at between 10 C to +10 C until approximatel
35、y 12 to34 of the p-xylene has frozen. Remove the sample and decant the liquid portion. Allow the p-xylene to thaw and repeat thecrystallization step on the remaining sample until the p-xylene is free of contamination (no peaks detected other than p-xylene)as indicated by gas chromatography.8.4.2 Fil
36、l a 100 mL volumetric flask approximately 34 full of the high purity p-xylene.8.4.3 Add 0.1 mL m-xylene.8.4.4 Add 0.01 mL of toluene, ethylbenzene, cumene, o-xylene, styrene, alpha methylstyrene, and phenylacetylene.8.4.5 Add 0.001 mL benzene and 1, 4-dioxane.8.4.6 Dilute to volume with high purity
37、parap-xylene.8.4.7 Impurities that are not present in the samples being analyzed may be omitted from the check sample.8.4.8 The purpose of the set-up check sample is to help determine the retention time of the various components and that theparap-xylene and metam-xylene are adequately separated. Thi
38、s sample should not be used for calibration.9. Hazards9.1 Consult current OSHA regulations, suppliers Safety Data Sheets, and local regulations for all materials used in this testmethod.10. Sampling10.1 Sample the material in accordance with Practice D3437.11. Preparation of Apparatus11.1 Follow man
39、ufacturers instructions for mounting and conditioning the column into the chromatograph and adjusting theinstrument to the conditions described in Table 1, allowing sufficient time for the equipment to reach equilibrium. See PracticesE260, E355, and E1510 for additional information on gas chromatogr
40、aphy practices and terminology.12. Calibration12.1 Prior to implementation of the ECN method, a laboratory should demonstrate that the equipment is set up properly usingan equipment set-up check sample. This sample should be used to: determine retention times of each component, and that theseparatio
41、n of metam-xylene from parap-xylene is satisfactory. See 6.1 for the definition of an adequate separation.6 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed bythe American Chemical Society, s
42、ee Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D7504 18313. Procedure13.1 Bring the sample to room temperature.13.2 Check the chromatography performance t
43、o make sure that the column is properly resolving peaks.13.3 Inject an appropriate amount of sample into the instrument.13.4 Review the chromatographic data system result. Measure the area of all peaks. The non-aromatics fraction includes allpeaks up to ethylbenzene except for the peaks assigned to
44、benzene and toluene. Sum together all the non-aromatic peaks as a totalarea. When either benzene or toluene is analyzed and 1,4-dioxane is required to be reported, the non-aromatic fraction does notinclude the peak assigned to 1,4-dioxane.NOTE 1A poorly resolved peak, such as p-xylene from high puri
45、ty ethylbenzene or m-xylene from high purity p-xylene, will often require a tangentskim from the neighboring peak.13.5 See Figs. 1-8 for representative chromatograms.14. Calculation or Interpretation of Results14.1 Using the ECN weight correction factors listed in Table 2, calculate the concentratio
46、n of each component as follows:Ci 51003Ai 3Ri!/(i51nAi 3Ri! (1)where:Ci = concentration for component i, weight %,Ai = peak area of component i, andRi = ECN correction factor for component i.14.2 Calculate the volume percent concentration of each component using the density in Table 2 as follows:Vi
47、51003Ci/Di!/(i51nCi/Di! (2)where:Vi = calculated vol % concentration of component i,TABLE 2 Effective Carbon Number Correction Factors andDensityComponentECNCorrectionFactorADensity at 20CNon Aromatics 1.0000 0.7255 (average)BBenzene 0.9095 0.8780CToluene 0.9195 0.8658CEthylbenzene 0.9271 0.8658Cp-X
48、ylene 0.9271 0.8597Cp-xylene 0.9271 0.8597Cm-Xylene 0.9271 0.8630Cm-xylene 0.9271 0.8630Co-Xylene 0.9271 0.8786Co-xylene 0.9271 0.8786CCumene 0.9329 0.8605C1,4-Dioxane 3.0774 1.0329DC9 + Aromatics 0.9329 0.8715E averageC9 + Aromatics 0.9329 0.8715E averageStyrene 0.9210 0.9048CC10 Aromatics 0.9376 0
49、.8694E averagep-diethylbenzene(PDEB)0.9376 0.8620EPhenylacetylene 0.8296 0.9300FAlpha-methylstyreneAMS0.9276 0.9077FA Correction factors are relative to n-heptane.B DS # 4A Physical Constants of Hydrocarbons C1 through C10, ASTM, 1971.Average of hexane, methylcyclopentane, methylcyclohexane, heptane, andethylcyclopentane.C Test Method D1555M.D Keith, L. H., Walters, D B., Compendium of Safety Data Sheets for Research andIndustrial Chemicals, Part II, VCH Publishers, Deerfield Beach, p. 726, 1985.E CRC Handbook of Chemistry and Physics, David R.
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