1、Designation: D7504 151D7504 16Standard 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 NOTEResearch Report information was added editorially in September 2015.1. Scope*1.1
3、 This test method covers the determination of total nonaromatic hydrocarbons 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
4、xylenes is also calculated. Similar test methods, using the internalstandard 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-xyl
5、ene, styrene and mixed xylenes may not bedistinguished from the non-aromatics and the concentrations are determined as a composite (see 6.1).1.3 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, eth
6、ylbenzene, benzene, and styrene.1.4 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 E29.1.5 The values stated in SI units are to be regarded as standard. No other uni
7、ts of measurement are included in this standard.1.6 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 and health practices and determine the applicability of regu
8、latorylimitations prior to use.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 MetricD2360 Test Method for Trace Impurities in Monocyclic Aromatic Hydr
9、ocarbons by Gas ChromatographyD3437 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 Gas ChromatographyD4790 Terminology of Aromatic Hydrocarbons and Related Chemica
10、lsD5060 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 Purity p-XyleneD5211 Specification for Xylenes for p-Xylene FeedstockD5917 Test Method for Trace Impur
11、ities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and ExternalCalibrationD6229 Test Method for Trace Benzene in Hydrocarbon Solvents by Capillary Gas Chromatography1 This test method is under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons and Related Chemicals and is t
12、he direct responsibility of SubcommitteeD16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Their Derivatives.Current edition approved July 1, 2015Aug. 1, 2016. Published July 2015August 2016. Originally approved in 2009. Last previous edition approved in 20122015 asD7504 12.D7504 151. DOI: 10.1520
13、/D7504-15E01.10.1520/D7504-16.2 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 standards Document Summary page on the ASTM website.3 The last approved version of
14、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 version. Becauseit may not be technically possible to adequately depict all changes a
15、ccurately, 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 section appears at the end of this standardCopyright ASTM International, 100 Barr Har
16、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D6563 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 Usi
17、ng 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 Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and RelationshipsE691 Practice for Conducting an Inter
18、laboratory 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
19、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 acapillary column. The peak area of each component is measured and adjusted using effective carbon number (ECN)5responsecorrectio
20、n factors. The concentration of each component is calculated based on its relative percentages of total adjustedpeak area and normalized 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-xylen
21、e, 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 internal quality control tool where these products are produced orare used. Typical impurities are: alkanes containi
22、ng 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 there may be unknown components that would be assigned inappropriateresponsecorrection factors and thus, the results
23、 may not be absolute.6. 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 concentra
24、tion must be determined, an alternate method such as Test Method D6229 must be selected to ensure an accurateassessment of the benzene concentration.6.2 The complete separation of p-xylene from ethylbenzene, or ethylbenzene and m-xylene from p-xylene can be difficult wheneither ethylbenzene or p-xyl
25、ene is analyzed, 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.7. Apparatus7.1 Chromatographic data system is required.7.2 ColumnsThe choice of column
26、is based on resolution 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
27、 having a flame 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 inte
28、gration for the 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 ch
29、romatograph. An automatic sampleinjection devise is highly recommended.7.5 Syringechromatographic, capable of delivering appropriate L volumes.4 Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.
30、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 1628. Reagents and Materials8.1 Purity of ReagentReagent grade chemica
31、ls shall be used in all 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
32、 grade may be used.8.2 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 hydroc
33、arbon.8.4 Calibration Check Standard. This standard may be purchased if desired.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, see Analar Standards for La
34、boratory 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 ParametersInlet SplitTemperature, C 270Column:Tubing fused silicaLength, m 60Internal diameter, mm 0.32Sta
35、tionary phase crosslinked polyethyleneglycolFilm thickness, m 0.25Column temperature programInitial temperature, C 60Initial time, min 10Programming rate, C/min 5Final, C 150Time 2, min 10Carrier gas helium or hydrogenLinear velocity, cm/s at 145C 20 helium or 45 hydrogenSplit ratio 100:1Sample size
36、, L 0.6Detector: flame ionizationTemperature, C 300Analysis time, min 38TABLE 2 Effective Carbon Number ResponseCorrection Factorsand DensityComponentECNResponse CorrectionFactorADensity at 20CNon Aromatics 1.0000 0.7255 (average)BBenzene 0.9100 0.8780CToluene 0.9200 0.8658CEthylbenzene 0.9275 0.865
37、8Cp-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 averageStyrene 0.91 0.9048CStyrene 0.9215 0.9048CC10 Aromatics 0.938 0.8694E averagep-diethylbenzene(PDEB)0.938 0.8620EA Response Correction factors are
38、 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 Chemi
39、cals, Part II, VCH Publishers, Deerfield Beach, p. 726, 1985.E CRC Handbook of Chemistry and Physics, David R. Lide, 88th Ed., 20072008.D7504 1639. Hazards9.1 Consult current OSHA regulations, suppliers Safety Data Sheets, and local regulations for all materials used in this testmethod.10. Sampling1
40、0.1 Sample the material in accordance with Practice D3437.11. Preparation of Apparatus11.1 Follow manufacturersmanufacturers instructions for mounting and conditioning the column into the chromatograph andadjusting the instrument to the conditions described in Table 1, allowing sufficient time for t
41、he equipment to reach equilibrium.See Practices E260, E355, and E1510 for additional information on 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 sy
42、nthetic mixture of known composition (Calibration check sample).13. Procedure13.1 Bring the sample to 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.13.4 Review the ch
43、romatographic data system result. Measure the area of all peaks. The non-aromatics fraction includes 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
44、 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 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 r
45、epresentative chromatograms.D7504 16414. Calculation or Interpretation of Results14.1 Using the ECN weight responsecorrection factors listed in Table 2, calculate the concentration of each component asfollows:FIG. 1 Typical Chromatogram of Synthetic BlendFIG. 2 Typical Chromatogram of TolueneD7504 1
46、65Ci 51003Ai 3Ri!/(i51nAi 3Ri! (1)where:Ci = concentration for component i, weight %,Ai = peak area of component i, andRi = ECN response factor for component i.Ri = ECN correction factor for component i.14.2 Calculate the volume percent concentration of each component using the density inTable 2 as
47、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.FIG. 3 Typical Chromatogram of Specification D5211, XylenesD7504 16615. Report15.1 Report individual impurities a
48、nd total non-aromatics, to the nearest 0.0001 %.15.1.1 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 required, report total xylenes to the nearest 0.0001 %. It is the sum of m-xylene, o-xylene, p-xylene, and et
49、hylbenzeneby industry convention.FIG. 4 Typical Chromatogram of Specification D5136, p-XyleneFIG. 5 Typical Chromatogram of BenzeneD7504 16715.2 For concentrations of impurities less than 0.0001 %,0.0002 %, report as 0.0001 %,0.0002 %, and consider as 0.0000 insummation of impurities.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 differ
