1、Designation:D750411 Designation: D7504 12Standard 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 oforig
2、inal adoption 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 the total nonarom
3、atic hydrocarbons and trace monocyclic aromatichydrocarbons in toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, benzene, and styrene by gas chromatography. Thepurity of toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, benzene, and stryene can also be calculated. Similar testmethods
4、, 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 Total aliphatic hydrocarbons containing 1 through 10 carbon atoms (methane through decanes) can be detected by thi
5、s testmethod at concentrations ranging from 0.0001 to 2.5000 weight %.1.2.1 A small amount of benzene in toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene, or styrene may not bedistinguished from the non-aromatics and the concentrations are determined as a composite (see 6.1).1.3 Monocyclic a
6、romatic hydrocarbon impurities containing 6 through 10 carbon atoms (benzene through C10aromatics) canbe detected by this test method at individual concentrations ranging from 0.0001 to 2.5000 weight %.1.4 In determining the conformance of the test results using this method to applicable specificati
7、ons, 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 units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any,
8、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.2. Referenced Documents2.1 ASTM Standards:2D841 Specification for Nitration Grade TolueneD1555M Tes
9、t 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 ChromatographyD3437 Practice for Sampling and Handling Liquid Cyclic ProductsD3797 Test Method for Analysis of o-X
10、ylene by Gas ChromatographyD4492 Test Method for Analysis of Benzene by Gas ChromatographyD4790 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 Capilla
11、ry Gas ChromatographyD5136 Specification for High Purity 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 b
12、y 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 Materials1This test method is under the jurisdiction of ASTM Committee
13、D16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of SubcommitteeD16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Their Derivatives.Current edition approved June 1, 2011. Published August 2011. Originally approved in 2009. Last previous edition approved in 2010
14、as D7504-10. DOI:10.1520/D7504-11.Current edition approved March 15, 2012. Published March 2012. Originally approved in 2009. Last previous edition approved in 2011 as D7504 - 11. DOI:10.1520/D7504-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Serv
15、ice at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This 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 previo
16、us version. 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 Chang
17、es section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.E29 Practice for Using Significant Digits in Test Data to Determine Conformance with SpecificationsE177 Practice for Use of the Terms Preci
18、sion and Bias in ASTM Test MethodsE260 Practice for Packed Column 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 Cap
19、illary Columns in Gas Chromatographs2.2 Other Document:OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.120033. 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 e
20、quipped with a flame ionization detector (FID) and acapillary column. The peak area of each component is measured and adjusted using effective carbon number (ECN)4responsefactors. The concentration of each component is calculated based on its relative percentages of total adjusted peak area andnorma
21、lized 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, ethylbenzene, benzene, and styrene used as chemical intermediates and solvents is often required. This testmethod is s
22、uitable 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 carbons atoms, benzene, toluene, ethylbenzene (EB), xylenes, andaromatic hydrocarbons containing nine carbon atoms or mo
23、re.5.2 This method may not detect all components and there may be unknown components that would be assigned inappropriateresponse factors and thus, the results may not be absolute.6. Interferences6.1 In some cases for toluene, mixed xylenes, p-xylene, o-xylene, ethylbenzene and styrene, it may be di
24、fficult to resolvebenzene from the nonaromatic hydrocarbons. Therefore the concentrations are determined as a composite. In the event that thebenzene concentration must be determined, an alternate method such as Test Method D6229 must be selected to ensure an accurateassessment of the benzene concen
25、tration.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-xylene is analyzed, respecively. The separation can be considered adequate if the distance from thebaseline to the valley between the two peak
26、s is not greater than 50 % of the peak height of lower of the two peaks.3Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.4Scanlon, J. T. and Willis, D. E., “Calculation of Flame Ionizat
27、ion Detector Relative Response Factors Using the Effective Carbon Number Concept,” Journal ofChromatographic Science, Vol. 23, August 1985, pp. 333339.TABLE 1 Recommended Method ParametersInlet SplitTemperature, C 270Column:Tubing fused silicaLength, m 60Internal diameter, mm 0.32Stationary phase cr
28、osslinked 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, L 0.6Detector:
29、 flame ionizationTemperature, C 300Analysis time, min 38D7504 1227. Apparatus7.1 Chromatographic data system is required.7.2 ColumnsThe choice of column is based on resolution requirements. Any column may be used that is capable of resolvingall significant impurities from the major component. The co
30、lumn 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 ionization detector and a splitter injector suitable for use with a fusedsilica capillary column may be used, provided the system
31、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 component. It shall have a splitinjection system that will not discriminate over the boiling range of the samples analyzed.
32、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. An automatic sampleinjection devise is highly recommended.7.5 Syringe, chromatographic, capable of delivering appropriate L volumes.8
33、. Reagents and Materials8.1 Purity of ReagentReagent grade chemicals 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,5wheresuch specifications are avai
34、lable. 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 less than 1 ppm, less than 0.5 ppmis preferred. Purify carrier, makeup and detector gases to remove oxygen, water, and hydrocarbons.
35、8.3 Air for the FID should contain less than 0.1 ppm total hydrocarbon.8.4 Calibration Check Standard. This standard may be purchased if desired.9. Hazards9.1 Consult current OSHA regulations, suppliers Material Safety Data Sheets, and local regulations for all materials used inthis test method.10.
36、Sampling10.1 Sample the material in accordance with Practice D3437.11. Preparation of Apparatus11.1 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 e
37、quipment to reach equilibrium. See PracticesE260, 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 synthe
38、tic 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 chroma
39、tographic 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 req
40、uired 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 repre
41、sentative chromatograms.14. Calculation or Interpretation of Results14.1 Using the ECN weight response factors listed in Table 2, calculate the concentration of each component as follows:5Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Sugg
42、estions 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.D7504 123Ci5 100 3 Ai3 Ri!
43、/(i51nAi3 R (1)Ci5 100 3 Ai3 Ri! /(i51nAi3 R (1)i D7504-12_1where:Ci= concentration for component i, weight %,Ai= peak area of component i, andRi= ECN response factor for component i.14.2 Calculate the volume percent concentration of each component using the density in Table 2 as follows:Vi5 100 3 C
44、i/ Di! /(i51nCi/ Di! D7504-12_2 (2)where:Vi= calculated vol % concentration of component i,Ci= calculated wt % concentration of component i from 14.1, andDi= density of component i .15. Report15.1 Report individual impurities and total non-aromatics, to the nearest 0.0001 %.15.1.1 If required, repor
45、t total C9+aromatics to the nearest 0.0001 %. It is the sum of cumene and all peaks emerging aftero-xylene.TABLE 2 Effective Carbon Number Response Factors andDensityComponent Response Factor (Weight)ADensity at 20CComponentECNResponse FactorADensity at 20CNon-aromatics 1.0000Non Aromatics 1.0000 0.
46、7255 (average)BBenzene 0.9100Benzene 0.9100 0.8780CToleune 0.9200Toluene 0.9200 0.8658CEthylbenzene 0.9275Ethylbenzene 0.9275 0.8658Cp-Xylene 0.9275p-Xylene 0.9275 0.8597Cm-Xylene 0.9275m-Xylene 0.9275 0.8630Co-Xylene 0.9275o-Xylene 0.9275 0.8786CCumene 0.9333Cumene 0.9333 0.8605C1,4-Dioxane 3.0800
47、1.0329DC9aromatics 0.9333C9+Aromatics 0.9333 0.8715EaverageStyrene 0.91Styrene 0.91 0.9048CC10aromatics 0.938C10Aromatics 0.938 0.8694Eaveragep-diethylbenzene (PDEB) 0.93801,4-dioxane 3.081,4-dioxane 08Ethyltoluene 0.93332-propenylbenzene 0.9178a methylstyrene 0.9178Phenylethyne 0.8925Phenylethyne 0
48、.89620EAResponse factors are relative to n-heptane.BDS#4APhysical Constants of Hydrocarbons C1through C10, ASTM, 1971.Average of hexane, methylcyclopentane, methylcyclohexane, heptane, and ethyl-cyclopentane.CTest Method D1555M.DKeith, L. H., Walters, D B., Compendium of Safety Data Sheets for Resea
49、rchand Industrial Chemicals, Part II, VCH Publishers, Deerfield Beach, p. 726, 1985.ECRC Handbook of Chemistry and Physics, David R. Lide, 88th Ed.,20072008.D7504 12415.1.2 If required, 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 0.0001 %, report as 0.0001 %, 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 0.0
