1、Designation: D 5917 09Standard 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 () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the totalnonaromatic hydrocarbons and
3、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, us
4、ing 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 xylen
5、es 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 concentration
6、sranging 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 stated in SI units are to be regarded asstandard. No other units of measur
7、ement 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 and health practices and determine the applica-bility of regulatory limit
8、ations prior to use. For specific hazardstatement, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D 841 Specification for Nitration Grade TolueneD 2306 Test Method for C8Aromatic Hydrocarbon Analy-sis by Gas Chromatography3D 2360 Test Method for Trace Impurities in MonocyclicAromatic Hydro
9、carbons by Gas ChromatographyD 3437 Practice for Sampling and Handling Liquid CyclicProductsD 4052 Test Method for Density and Relative Density ofLiquids by Digital Density MeterD 4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsD 4790 Terminology of Aromatic Hydrocarbons
10、 and Re-lated ChemicalsD 5136 Specification for High Purity p-XyleneD 5211 Specification for Xylenes for p-Xylene FeedstockD 6526 Test Method for Analysis of Toluene by CapillaryColumn Gas ChromatographyD 6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Re
11、lated Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE 260 Practice for Packed Column Gas ChromatographyE 355 Practice for Gas Chromatography Terms and Rela-tionshipsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Pr
12、ecision of a Test MethodE 1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs2.2 Other Document:1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D1
13、6.04 on Instrumental Analysis.Current edition approved Jan. 1, 2009. Published January 2009. Originallyapproved in 1996. Last previous edition approved in 2002 as D 5917 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For A
14、nnual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM Internation
15、al, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.OSHA Regulations, 29CFR paragraphs 1910.1000 and1910.120043. Terminology3.1 See Terminology D 4790 for definitions of terms used inthis test method.3.2 Mixed xylenes are a mixture of C8aromatics includingm-xylene
16、, 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 injected into a gas chromatograph equipped with aflam
17、e 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 sum of the impurities found from 100.00.Results
18、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. This test method is suitable forsetting specificat
19、ions 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 carbon atoms.5.1.1 Refer to Test Method D 2306 for
20、 determining the C8aromatic 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 themat
21、erial being examined.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 a
22、nd p-xylene, it may 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 6526must be selected to ensure an accurate asse
23、ssment of thebenzene 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 instru
24、ment having a flameionization 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 resol
25、utionrequirements. 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
26、InjectorThe specimen 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.
27、1 Purity of ReagentReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society,5where such specifications are available.8.2 Carrier GasChroma
28、tographic grade helium or hydro-gen, 99.999 % is recommended. Purify carrier, makeup anddetector gases to remove oxygen, water, and hydrocarbons.4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.
29、gpo.gov.5Reagent Chemicals, 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 Ph
30、armacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Typical Method ParametersInlet SplitTemperature, C 270Column:Tubing fused silicaLength, m 60Internal diameter, mm 0.32Stationary phase crosslinked polyethylene glycolFilm thickness, m 0.25Column temper
31、ature 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 1.0Detector: flame ionizationTemperature, C 300Analysis time, min 30D591709
32、28.3 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 purified by recrystallization. Toprepare 1.9 L of high purity p-xylene, begin with approxi-
33、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 solid portion is thepurified p-xylene. Allow the p-xylene to thaw and repeat thecrystall
34、ization 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-xylene, m-xylene, andcumene. If applicable, the calibration may include paradieth-ylbe
35、nzene (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 adjusted for the presence of theimpurities.9. Hazards9.1 Consult current OSHA regulations, s
36、uppliers MaterialSafety Data Sheets, and local 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 chromatograp
37、h and adjustingthe instrument to the conditions 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 hig
38、h 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 compounds must be brought to thesame temperature before mixing. Refer to Table 2
39、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 or greater, withexception of PDEB. If PDEB is included in the calibration,
40、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 25C.12.2 Using the exact volumes and densities in Table 2,calculate the weight % concentration for each impurity in
41、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= concentration of impurity i, weight %.12.2.1 Alternatively, calibration standards may b
42、e used thathave been gravimetrically prepared 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
43、mixture as follows:RFi5 Ci/ Ai(2)where:RFi= response 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 d
44、eviation for RFof eachimpurity using a scientific calculator or spreadsheet program.Determine the coefficient of variation for each RFas follows:CVi5 100 SDi/ Avgi(3)TABLE 2 Preparation of Calibration BlendCompound DensityARecommendedVol, LResulting Concentration(including PDEB)Resulting Concentrati
45、on(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-Xylene 0.876 100 0.100 0.102 0.100 0.102Cumene 0.857 20 0.020 0.02
46、0 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 4A, 1971.D5917093where:CVi= coefficient of variation for RFi,SDi=
47、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 not exceed 10 %.13. Procedure13.1 Bring the sample and calibration mixtures to ide
48、nticaltemperatures, preferably 25C. Make sure that the temperatureof the sample is consistent with that of the calibration standardprepared in Section 12.13.2 Depending upon the actual chromatographs operatingconditions, inject an appropriate amount of sample into theinstrument. The injection amount
49、 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 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 a total area. The C9aromatics fraction includescumene and all peaks emerging after o-xylene, with exceptionof PDEB. Sum together
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