1、Designation: D5917 151Standard Test Method forTrace Impurities in Monocyclic Aromatic Hydrocarbons byGas Chromatography and External Calibration1This standard is issued under the fixed designation D5917; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he 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.1NOTEResearch Report information was added editorially in September 2015.1. Scope*1.1 This test m
3、ethod covers the determination of the totalnonaromatic hydrocarbons and trace monocyclic aromatichydrocarbons in toluene, mixed xylenes, and p-xylene by gaschromatography. The purity of toluene, mixed xylenes, orp-xylene can also be calculated. Calibration of the gas chro-matographic system is done
4、by the external standard calibra-tion technique. A similar test method, using the internalstandard calibration technique, is Test Method D2360.1.2 Total aliphatic hydrocarbons containing 1 through 10carbon atoms (methane through decanes) can be detected bythis test method at concentrations ranging f
5、rom 0.001 to 2.500weight %.1.2.1 A small amount of benzene in mixed xylenes orp-xylenes may not be distinguished from the nonaromatics andthe concentrations are determined as a composite (see 6.1).1.3 Monocyclic aromatic hydrocarbon impurities containing6 through 10 carbon atoms (benzene through C10
6、aromatics)can be detected by this test method at individual concentrationsranging from 0.001 to 1.000 weight %.1.4 In determining the conformance of the test results toapplicable specifications, results shall be rounded off in accor-dance with the rounding-off method of Practice E29.1.5 The values s
7、tated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety
8、and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatement, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D841 Specification for Nitration Grade TolueneD2360 Test Method for Trace Impurities in MonocyclicAromatic Hydrocarbons
9、 by Gas ChromatographyD3437 Practice for Sampling and Handling Liquid CyclicProductsD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsD4790 Terminology of Aromatic Hydrocarb
10、ons and RelatedChemicalsD5136 Specification for High Purity p-XyleneD5211 Specification for Xylenes for p-Xylene FeedstockD6526 Test Method for Analysis of Toluene by CapillaryColumn Gas ChromatographyD6563 Test Method for Benzene, Toluene, Xylene (BTX)Concentrates Analysis by Gas ChromatographyD680
11、9 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms a
12、nd Relation-shipsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and
13、 Related Chemicals and is the direct responsibility ofSubcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and TheirDerivatives.Current edition approved Feb. 1, 2015. Published May 2015. Originallyapproved in 1996. Last previous edition approved in 2012 as D5917 12. DOI:10.1520/D5917-15E01.
14、2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this stan
15、dardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.2 Other Document:OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120033. Terminology3.1 See Terminology D4790 for definitions of terms used inthis test method.3.2 Mixed xylen
16、es are a mixture of C8aromatics includingm-xylene, o-xylene, and p-xylene. Industry convention in-cludes ethylbenzene as a mixed xylene though ethylbenzeneis not technically a xylene. Styrene is excluded.4. Summary of Test Method4.1 A repeatable volume of the specimen to be analyzed isprecisely inje
17、cted into a gas chromatograph equipped with aflame ionization detector (FID).The peak area of each impurityis measured. Concentration of each impurity is determinedfrom the linear calibration curve of peak area versus concen-tration. Purity by gas chromatography (GC) is calculated bysubtracting the
18、sum of the impurities found from 100.00.Results are reported in weight percent.5. Significance and Use5.1 Determining the type and amount of hydrocarbon im-purities remaining from the manufacture of toluene, mixedxylenes, and p-xylenes used as chemical intermediates andsolvents is often required. Th
19、is test method is suitable forsetting specifications and for use as an internal quality controltool where these products are produced or are used. Typicalimpurities are: alkanes containing 1 to 10 carbons atoms,benzene, toluene, ethylbenzene (EB), xylenes, and aromatichydrocarbons containing nine ca
20、rbon atoms.5.2 Purity is commonly reported by subtracting the deter-mined expected impurities from 100.00. However, a gaschromatographic analysis cannot determine absolute purity ifunknown or undetected components are contained within thematerial being examined.5.3 This test method is similar to Tes
21、t Method D2360,however, interlaboratory testing has indicated a bias may existbetween the two methods. Therefore the user is cautioned thatthe two methods may not give comparable results.6. Interferences6.1 In some cases for mixed xylenes and p-xylene, it may bedifficult to resolve benzene from the
22、nonaromatic hydrocar-bons. Therefore the concentrations are determined as a com-posite. In the event that the benzene concentration must bedetermined, an alternate method such as Test Method D6526must be selected to ensure an accurate assessment of thebenzene concentration.6.2 Complete separation of
23、 ethylbenzene and m-xylenefrom p-xylene is difficult and can be considered adequate if thedistance from baseline to valley between peaks is not greaterthan 50 % of the peak height of the impurity.7. Apparatus7.1 Gas ChromatographAny instrument having a flameionization detector that can be operated a
24、t the conditions givenin Table 1. The system shall have sufficient sensitivity to obtaina minimum peak height response for 0.001 weight % impurityof twice the height of the background noise.7.2 ColumnsThe choice of column is based on resolutionrequirements. Any column may be used that is capable ofr
25、esolving all significant impurities from the major component.The column and conditions described in Table 1 have beenused successfully and shall be used as a referee in cases ofdispute.7.3 RecorderElectronic integration is recommended.7.4 InjectorThe specimen must be precisely and repeat-ably inject
26、ed into the gas chromatograph.An automatic sampleinjection device is highly recommended although manualinjection can be employed if the criteria in 12.7 can besatisfied.7.5 Volumetric Flask, 100-mL capacity.7.6 Syringe, 100 L.8. Reagents8.1 Purity of ReagentReagent grade chemicals shall beused in al
27、l tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society,4where such specifications are available.8.2 Carrier GasChromatographic grade helium orhydrogen, 99.999 % is recommended. P
28、urify carrier, fuel and3Available 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.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For sugges
29、tions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Recommended Operating C
30、onditionsInlet SplitTemperature, C 270Column:Tubing fused silicaLength, m 60Internal diameter, mm 0.32Stationary phase crosslinked polyethylene glycolFilm thickness, m 0.25Column temperature programInitial temperature, C 60Initial time, min 10Programming rate, C/min 5Final, C 150Time 2, min 10Carrie
31、r gas Helium or HydrogenLinear velocity, cm/s at 145C 20 Helium or 45 HydrogenSplit ratio 100:1Sample size, L 1.0Detector: flame ionizationTemperature, C 300Analysis time, min 30D5917 1512makeup gases by adding traps to reduce the concentration ofany remaining oxygen, water, and hydrocarbons. Purify
32、 air byadding traps to reduce the concentration of any remaininghydrocarbons and water.8.3 Air, Chromatographic grade, containing less than 0.1ppm THC.8.4 High Purity p-Xylene, 99.999 weight % or greaterpurity.8.4.1 Most p-xylene is available commercially at a purityless than 99.9 % and can be purif
33、ied by recrystallization. Toprepare 1.9 L of high purity p-xylene, begin with approxi-mately 3.8 L of material and cool in a flammable storagefreezer at 10 6 5C until approximately12 to34 of thep-xylene has frozen. This should require about 5 h. Remove thesample and decant the liquid portion. The so
34、lid portion is thepurified p-xylene. Allow the p-xylene to thaw and repeat thecrystallization procedure on the remaining sample until thep-xylene is free of contamination as indicated by gas chroma-tography.8.5 Pure compounds for calibration, shall include n-nonane,benzene, toluene, ethylbenzene, o-
35、xylene, m-xylene, andcumene. If applicable, the calibration may include paradieth-ylbenzene (PDEB). The purity of all reagents should be 99weight %. If the purity is less than 99 %, the concentration andidentification of impurities must be known so that the compo-sition of the standard can be adjust
36、ed for the presence of theimpurities.9. Hazards9.1 Consult current OSHA regulations, suppliers SafetyData Sheets, and local regulations for all materials used in thistest method.10. Sampling10.1 Sample the material in accordance with PracticeD3437.11. Preparation of Apparatus11.1 Follow manufacturer
37、s instructions for mounting andconditioning the column into the chromatograph and adjustingthe instrument to the conditions described in Table 1, allowingsufficient time for the equipment to reach equilibrium. SeePractices E260, E355, and E1510 for additional information ongas chromatography practic
38、es and terminology.12. Calibration12.1 Prepare a synthetic mixture of high purity p-xylenecontaining impurities at concentrations representative of thoseexpected in the samples to be analyzed. The volume of eachhydrocarbon impurity must be measured to the nearest 1 Land all liquid reference compound
39、s must be brought to thesame temperature before mixing. Refer to Table 2 for anexample of a calibration blend. n-Nonane will represent thenonaromatic fraction, o-xylene the o-xylene fraction, m-xylenethe m-xylene fraction. Cumene will represent the aromatichydrocarbons containing nine carbon atoms o
40、r greater, withexception of PDEB. If PDEB is included in the calibration,PDEB will represent PDEB.12.1.1 Prior to preparing the calibration standard, all refer-ence compounds and any samples to be analyzed must bebrought to the same temperature, preferably ambient or 20C.12.2 Using the exact volumes
41、 and densities in Table 2,calculate the weight % concentration for each impurity in thecalibration blend as follows:Ci5 100 DiVi/VtDp! (1)where:Di= density of impurity i from Table 2,Vi= volume of impurity i, mL,Dp= density of p-xylene from Table 2,Vt= total volume of standard blend, mL, andCi= conc
42、entration of impurity i, weight %.12.2.1 Alternatively, calibration standards may be used thathave been gravimetrically prepared in accordance with PracticeD4307.12.3 Inject the resulting solution from 12.1 into thechromatograph, collect and process the data. A typical chro-matogram is illustrated i
43、n Fig. 1.12.4 Determine the response factor for each impurity in thecalibration mixture as follows:TABLE 2 Preparation of Calibration BlendCompound DensityARecommendedVol, LResulting Concentration (includingPDEB)Resulting Concentration (excludingPDEB)Volume % Weight % Volume % Weight %p-Xylene 0.861
44、 99.60-99.62 ml 99.60 99.60 99.62 99.62Benzene 0.879 20 0.020 0.020 0.020 0.020Toluene 0.867 20 0.020 0.020 0.020 0.020Ethylbenzene 0.867 100 0.100 0.100 0.100 0.100o-Xylene 0.880 100 0.100 0.102 0.100 0.102Cumene 0.862 20 0.020 0.020 0.020 0.020n-Nonane 0.718 20 0.020 0.017 0.020 0.017m-Xylene 0.86
45、4 100 0.100 0.101 0.100 0.101PDEB 0.866 20 0.020 0.020 n/a n/aADensity at 20C. Values obtained from “Physical Constants of Hydrocarbons C1to C10;” ASTM Publication DS 4A, 1971.D5917 1513RFi5 Ci/Ai(2)where:RFi= response factor for impurity i,Ai= peak area of impurity i, andCi= concentration of impuri
46、ty i, as calculated in 12.2,weight %.12.5 Analyze the calibration solution(s) a minimum of threetimes and calculate an average RF.12.6 Determine the sample standard deviation for RF ofeach impurity using a scientific calculator or spreadsheetprogram. Determine the coefficient of variation for each R
47、F asfollows:CVi5 100 SDi/Avgi(3)where:CVi= coefficient of variation for RFi,SDi= standard deviation for RFi, andAvgi= average RF of impurity i.12.7 The coefficient of variation for the response factor ofany impurity, as calculated from a minimum of three succes-sive analyses of the standard, shall n
48、ot exceed 10 %.13. Procedure13.1 Bring the sample and calibration mixtures to identicaltemperatures, preferably ambient or 20C. Make sure that thetemperature of the sample is consistent with that of thecalibration standard prepared in Section 12.13.2 Depending upon the actual chromatographs operatin
49、gconditions, inject an appropriate amount of sample into theinstrument. The injection amount shall be identical to theamount used in 12.3 and must be consistent with thoseconditions used to meet the criteria in 12.7.14. Calculations14.1 Measure the area of all peaks except the major com-ponent(s). Measurements on the sample must be consistentwith those made on the calibration blend. Total non-aromaticsare defined as all components eluting before o-xylene, exclud-ing benzene, toluene, ethylbenzene, p-xylene, m-xylene, andcumene (IPBZ in Fig. 1).T
