1、Designation: D 5917 02Standard Test Method forTrace Impurities in Monocyclic Aromatic Hydrocarbons byGas Chromatography and External Calibration1This standard is issued under the fixed designation D 5917; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope *1.1 This test method covers the determination of the totalnonaromatic hydrocarbons an
3、d trace monocyclic aromatichydrocarbons in toluene, mixed xylenes, and p-xylenes by gaschromatography. The purity of toluene, mixed xylenes, orp-xylenes can also be calculated. Calibration of the gaschromatographic system is done by the external standardcalibration technique. A similar test method,
4、using the internalstandard calibration technique, is Test Method D 2360.1.2 Total aliphatic hydrocarbons containing 1 through 10carbon atoms (methane through decanes) can be detected bythis test method at concentrations ranging from 0.001 to 2.500weight %.1.2.1 A small amount of benzene in mixed xyl
5、enes 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 C10aromatics)can be detected by this test method at individual concentrati
6、onsranging from 0.001 to 1.000 weight %.1.4 The following applies to all specified limits in this testmethod: for purposes of determining conformance with thistest method, an observed value or a calculated value shall berounded off “to the nearest unit” in the last right-hand digitused in expressing
7、 the specification limit, in accordance withthe rounding-off method of Practice E 29.1.5 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 and health practices an
8、d determine the applica-bility of regulatory limitations prior to use. For specific hazardstatement, see Section 9.2. Referenced Documents2.1 ASTM Standards:D 841 Specification for Nitration Grade Toluene2D 2306 Test Method for C8Hydrocarbon Analysis by GasChromatography2D 2360 Test Method for Trace
9、 Impurities in MonocyclicAromatic Hydrocarbons by Gas Chromatography2D 3437 Practice for Sampling and Handling Liquid CyclicProducts2D 4052 Test Method for Density and Relative Density ofLiquids by Digital Density Meter3D 4307 Practice for Preparation of Liquid Blends for Use asAnalytical Standards3
10、D 4534 Test Method for Benzene Content of Cyclic Prod-ucts by Gas Chromatography2D 4790 Terminology of Aromatic Hydrocarbons and Re-lated Chemicals2D 5136 Specification for High Purity p-Xylene2D 5211 Specification for Xylenes for p-Xylene Feedstock2E 29 Practice for Using Significant Digits in Test
11、 Data toDetermine Conformance with Specifications4E 260 Practice for Packed Column Gas Chromatography5E 355 Practice for Gas Chromatography Terms and Rela-tionships5E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method4E 1510 Practice for Installing Fused
12、Silica Open TubularCapillary Columns in Gas Chromatographs52.2 Other Document:OSHA Regulations, 29 CFR, paragraphs 1910.1000 and1910.120063. Terminology3.1 See Terminology D 4790 for definitions of terms used inthis test method.4. Summary of Test Method4.1 A repeatable volume of the specimen to be a
13、nalyzed isprecisely injected into a gas chromatograph equipped with aflame ionization detector (FID). The peak area of each impurityis measured. Concentration of each impurity is determined1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals
14、 and is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved Oct. 10, 2002. Published December 2002. Originallypublished as D 5917 96. Last previous edition D 5917 99.2Annual Book of ASTM Standards, Vol 06.04.3Annual Book of ASTM Standards, Vol 05.02.4Ann
15、ual Book of ASTM Standards, Vol 14.02.5Annual Book of ASTM Standards, Vol 03.06.6Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM I
16、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.from the linear calibration curve of peak area versus concen-tration. Purity by gas chromatography (GC) is calculated bysubtracting the sum of the impurities found from 100.00.Results are reported in we
17、ight 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. This test method is suitable forsetting specifications and for use a
18、s 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 carbon atoms.5.1.1 Refer to Test Method D 2306 for determining the C
19、8aromatic hydrocarbon distribution in mixed xylenes.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 examin
20、ed.5.3 This test method is similar to Test Method D 2360,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 ma
21、y bedifficult to resolve benzene from the 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 D 4534must be selected to ensure an accurate assessment of thebenze
22、ne concentration.6.2 Complete separation of 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 flam
23、eionization detector that can be operated at 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.
24、 Any column may be used that is capable ofresolving 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 specim
25、en must be precisely and repeat-ably injected 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 Reage
26、ntReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,7where such specifications are available.8.2 Carrier GasChromatographic grade
27、 helium or hydro-gen is recommended.8.3 High Purity p-Xylene, 99.999 weight % or greaterpurity.8.3.1 Most p-xylene is available commercially at a purityless than 99.9 % and can be purified by recrystallization. Toprepare 1.9 L of high purity p-xylene, begin with approxi-mately 3.8 L of material and
28、cool in a flammable storagefreezer at 10 6 5C until approximately12to34 of thep-xylene has frozen. This should require about 5 h. Remove thesample and decant the liquid portion. The solid portion is thepurified p-xylene. Allow the p-xylene to thaw and repeat thecrystallization procedure on the remai
29、ning sample until thep-xylene is free of contamination as indicated by gas chroma-tography.8.4 Pure compounds for calibration, shall include n-nonane,benzene, toluene, ethylbenzene, o-xylene, m-xylene, andcumene. If applicable, the calibration may include paradieth-ylbenzene (PDEB). The purity of al
30、l 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 adjusted for the presence of theimpurities.9. Hazards9.1 Consult current OSHA regulations, suppliers Material7Reagent Chem
31、icals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions 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 Nationa
32、l Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Method ParametersInlet SplitTemperature, C 270Column:Tubing fused silicaLength, m 60Internal diameter, mm 0.32Stationary phase crosslinked polyethylene glycolFilm thickness, m 0.25Column temperature programInitial temperat
33、ure, 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 1.0Detector: flame ionizationTemperature, C 300Analysis time, min 30D5917022Safety Data Sheets, and loca
34、l regulations for all materials usedin this test method.10. Sampling10.1 Sample the material in accordance with PracticeD 3437.11. Preparation of Apparatus11.1 Follow manufacturers instructions for mounting andconditioning the column into the chromatograph and adjustingthe instrument to the conditio
35、ns described in Table 1, allowingsufficient time for the equipment to reach equilibrium. SeePractices E 260, E 355, and E 1510 for additional informationon gas chromatography practices and terminology.12. Calibration12.1 Prepare a synthetic mixture of high purity p-xylenecontaining impurities at con
36、centrations 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 compounds must be brought to thesame temperature before mixing. Refer to Table 2 for anexample of a calibration blend. n-Nonan
37、e will represent thenonaromatic fraction, o-xylene the o-xylene fraction, m-xylenethe m-xylene fraction. Cumene will represent the aromatichydrocarbons containing nine carbon atoms or greater, withexception of PDEB. If PDEB is included in the calibration,PDEB will represent PDEB.12.1.1 Prior to prep
38、aring the calibration standard, all refer-ence compounds and any samples to be analyzed must bebrought to the same temperature, preferably 25C.12.2 Using the exact volumes and densities in Table 2,calculate the weight % concentration for each impurity in thecalibration blend as follows:Ci5 100 DiVi/
39、 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= concentration of impurity i, weight %.12.2.1 Alternatively, calibration standards may be used thathave been gravimetrically prepared
40、 in accordance with PracticeD 4307.12.3 Inject the resulting solution from 12.1 into the chro-matograph, collect and process the data. A typical chromato-gram is illustrated in Fig. 1.12.4 Determine the response factor for each impurity in thecalibration mixture as follows:RFi5 Ci/ Ai(2)where:RFi= r
41、esponse factor for impurity i,Ai= peak area of impurity i, andCi= concentration of impurity 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 scien
42、tific calculator or spreadsheetprogram. Determine the coefficient of variation for each RF 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 imp
43、urity, as calculated from a minimum of three succes-sive analyses of the standard, shall not exceed 10 %.13. Procedure13.1 Bring the sample and calibration mixtures to identicaltemperatures, preferably 25C. Make sure that the temperatureof the sample is consistent with that of the calibration standa
44、rdprepared in Section 12.13.2 Depending upon the actual chromatographs operatingconditions, 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 12.7.13.3
45、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. The nonaromaticfraction includes all peaks up to toluene (except for the peakassigned as benzene). Sum together all the nonaromatic peaksand report as
46、a total area. The C9aromatics fraction includescumene and all peaks emerging after o-xylene, with exceptionof PDEB. Sum together all the C9aromatic peaks and report asa total area. If PDEB is included in the calibration, reportPDEB.TABLE 2 Preparation of Calibration BlendCompound DensityARecommended
47、Vol, LResulting Concentration(including PDEB)Resulting Concentration(excluding PDEB)Volume % Weight % Volume % Weight %p-Xylene 0.857 99.60-99.62 ml 99.60 99.60 99.62 99.62Benzene 0.874 20 0.020 0.020 0.020 0.020Toluene 0.862 20 0.020 0.020 0.020 0.020Ethylbenzene 0.863 100 0.100 0.100 0.100 0.100o-
48、Xylene 0.876 100 0.100 0.102 0.100 0.102Cumene 0.857 20 0.020 0.020 0.020 0.020n-Nonane 0.714 20 0.020 0.017 0.020 0.017m-Xylene 0.864 100 0.100 0.101 0.100 0.101PDEB 0.862 20 0.020 0.020 n/a n/aADensity at 25C. Values obtained from “Physical Constants of Hydrocarbons C1to C10”; ASTM Publication DS
49、4A, 1971.D591702313.4 A poorly resolved peak, such as m-xylene, will oftenrequire a tangent skim from the neighboring peak. Makeconsistent measurements on the specimen and calibrationchromatograms for tangents or poorly resolved peaks.13.5 Fig. 2 illustrates the analysis of Specification D 841,Toluene. Fig. 3 illustrates the analysis of Specification D 5211,Mixed Xylene. Fig. 4 illustrates the analysis of SpecificationD 5136, p-xylene.14. Calculations14.1 Calculate the weight percent concentration of the totalnonaromatics and each impurity as follows. Use
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