1、Designation: D7504 16D7504 17Standard 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 adoptio
2、n 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 hydrocarbon
3、s 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 internalstandar
4、d calibration technique and the external standard calibration technique, are Test Methods D2360, D3797, D4492, D5060,D5135, D5917, and D6563 respectively.1.2 A small amount of benzene in toluene, ethylbenzene, p-xylene, o-xylene, styrene and mixed xylenes may not bedistinguished from the non-aromati
5、cs and the concentrations are determined as a composite (see 6.1).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, o-xylene, ethylbenzene, benzene, and styrene.1.3 In determining the conformance of the t
6、est 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. No other units of measurement are included in this standard.1.5 This standard does not
7、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 and health practices and determine the applicability of regulatorylimitations prior to use.1.6 This international standard was develope
8、d in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2
9、.1 ASTM Standards:2D841 Specification for Nitration Grade TolueneD1555M Test Method for Calculation of Volume and Weight of Industrial Aromatic Hydrocarbons and Cyclohexane MetricD2360 Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography (Withdrawn 2016)3D3437 P
10、ractice 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 Gas ChromatographyD4790 Terminology of Aromatic Hydrocarbons and Related ChemicalsD5060 Test Method for Determining I
11、mpurities in High-Purity Ethylbenzene by Gas ChromatographyD5135 Test Method for Analysis of Styrene by Capillary Gas ChromatographyD5136 Specification for High Purity p-XyleneD5211 Specification for Xylenes for p-Xylene Feedstock1 This test method is under the jurisdiction of ASTM Committee D16 on
12、Aromatic Hydrocarbons Aromatic, Industrial, Specialty and Related Chemicals and is the directresponsibility of Subcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Their Derivatives.Current edition approved Aug. 1, 2016April 1, 2017. Published August 2016April 2017. Originally approved
13、in 2009. Last previous edition approved in 20152016 asD7504 15D7504 16.1. DOI: 10.1520/D7504-16.10.1520/D7504-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the
14、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 standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous ve
15、rsion. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes se
16、ction appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D5917 Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and ExternalCalibrationD6229 Test Method for Tra
17、ce Benzene in Hydrocarbon Solvents by Capillary Gas ChromatographyD6563 Test Method for Benzene, Toluene, Xylene (BTX) Concentrates Analysis by Gas ChromatographyD6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related MaterialsE29 Practice for Using Sig
18、nificant 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 Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and RelationshipsE691 Practice for Conducting an Interlabora
19、tory 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 Regulations, 29 CFR paragraphs 1910.1000 and 1910.1200 43. Terminology3.1 See Terminology D4790 for definitions of terms used i
20、n 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 acapillary column. The peak area of each component is measured and adjusted using effective carbon number (ECN)5 correctionfactors. The
21、 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 Determining the type and amount of hydrocarbon impurities remaining from the manufacture of toluene, mixed xylenes,p-xylene, o-xylene, e
22、thylbenzene, benzene, and styrene used as chemical intermediates and solvents is often required. This testmethod is suitable for setting specifications and for use as an internal quality control tool where these products are produced orare used. Typical impurities are: alkanes containing 1 to 10 car
23、bons atoms, benzene, toluene, ethylbenzene (EB), xylenes, andaromatic hydrocarbons containing nine carbon atoms or more.5.2 This method may not detect all components and there may be unknown components that would be assigned inappropriatecorrection factors and thus, the results may not be absolute.6
24、. Interferences6.1 In some cases for toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene and styrene, it may be difficult to resolvebenzene from the nonaromatic hydrocarbons. Therefore the concentrations are determined as a composite. In the event that thebenzene concentration must be determine
25、d, an alternate method such as Test Method D6229 must be selected to ensure an accurateassessment of the benzene concentration.6.1 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 analyzed, respe
26、ctively. 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.7. Apparatus7.1 Chromatographic data system is required.7.2 ColumnsThe choice of column is based on resolution
27、 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 flame ioniza
28、tion 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 the major
29、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 1.4 Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Ma
30、il 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.D7504 1727.4 InjectorTh
31、e specimen must be precisely and repeatably injected into the gas chromatograph. 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 al
32、l tests. Unless otherwise indicated, it is intended that allreagents shall conform 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
33、 Carrier Gas, Makeup Gas and Detector Gases 99.999 % Pure. Oxygen in carrier gas 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 Calibration
34、Check Standard. This standard may be purchased if desired.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 Apparatus1
35、1.1 Follow manufacturers 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
36、gas chromatography practices and terminology.12. Calibration12.1 Prior to implementation of the ECN method, a laboratory should demonstrate that acceptable precision and bias can beobtained using a synthetic mixture of known composition (Calibration check sample).13. Procedure13.1 Bring the sample t
37、o room temperature.13.2 Check the chromatography performance to make sure that the column is properly resolving peaks.13.3 Inject an appropriate amount of sample into the instrument.6 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggesti
38、ons on the testing of reagents not listed bythe American Chemical Society, see 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.TABLE 1 Recommended Method Para
39、metersInlet 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, min 10Carrier ga
40、s 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 17313.4 Review the chromatographic data system result. Measure the area of all peaks. The non-aromatics fraction include
41、s allpeaks up to ethylbenzene except for the peaks assigned to 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-dioxan
42、e.NOTE 1A poorly resolved peak, such as p-xylene from high purity 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 c
43、orrection factors listed in Table 2, calculate the concentration 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 concentratio
44、n of each component using the density in Table 2 as follows:Vi 51003Ci/Di!/(i51nCi/Di! (2)where:Vi = calculated vol % concentration of component i,Ci = calculated wt % concentration of component i from 14.1, andDi = density of component i.TABLE 2 Effective Carbon Number Correction Factors andDensity
45、ComponentECNCorrectionFactorADensity at 20CNon Aromatics 1.0000 0.7255 (average)BBenzene 0.9100 0.8780CToluene 0.9200 0.8658CEthylbenzene 0.9275 0.8658Cp-Xylene 0.9275 0.8597Cm-Xylene 0.9275 0.8630Co-Xylene 0.9275 0.8786CCumene 0.9333 0.8605C1,4-Dioxane 3.0800 1.0329DC9 + Aromatics 0.9333 0.8715E av
46、erageStyrene 0.9215 0.9048CC10 Aromatics 0.938 0.8694E averagep-diethylbenzene(PDEB)0.938 0.8620EA 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, andethylcyclopent
47、ane.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. Lide, 88th Ed., 20072008.D7504 17415. Report15.1 Report individual i
48、mpurities and total non-aromatics, to the nearest 0.0001 %.FIG. 1 Typical Chromatogram of Synthetic BlendFIG. 2 Typical Chromatogram of TolueneD7504 17515.1.1 If required, report total C9+ aromatics to the nearest 0.0001 %. It is the sum of cumene and all peaks emerging aftero-xylene.15.1.2 If requi
49、red, report total xylenes to the nearest 0.0001 %. It is the sum of m-xylene, o-xylene, p-xylene, and ethylbenzeneby industry convention.15.2 For concentrations of impurities less than 0.0002 %, report as 0.0002 %, and consider as 0.0000 in summation ofimpurities.15.3 Report the total impurities to the nearest 0.01 %.15.4 Report purity as “purity (by GC)” to the nearest 0.01 %.16. Precision and Bias716.1 An ILS was conducted which included 14 laboratories analyzing 7 different materials. Each material was at 4 differentlevels and each level was
