1、Designation: D 2360 08Standard Test Method forTrace Impurities in Monocyclic Aromatic Hydrocarbons byGas Chromatography1This standard is issued under the fixed designation D 2360; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers th
3、e determination of the totalnonaromatic hydrocarbons, and trace monocyclic aromatichydrocarbons in the purity of toluene and mixed xylenes by gaschromatography.1.2 Nonaromatic aliphatic hydrocarbons containing 1through 10 carbon atoms (methane through decanes) can bedetected by this test method at c
4、oncentrations ranging from0.001 % to 2.500 weight %.1.2.1 A small amount of benzene in mixed xylenes may notbe distinguished from the nonaromatics and the concentrationsare determined as a composite.1.3 Monocyclic aromatic hydrocarbon impurities containing6 through 9 carbon atoms (benzene through C9
5、aromatics) canbe 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 usingthis method to applicable specifications, results shall berounded off in accordance with the rounding-off method ofPractice E29
6、.1.5 The values stated 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 app
7、ro-priate safety 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:2D 841 Specification for Nitration Grade TolueneD 3437 Practice for Sampling and Handling Liquid Cyclic
8、ProductsD 3797 Test Method for Analysis of o-Xylene by GasChromatographyD 3798 Test Method for Analysis of p-Xylene by GasChromatographyD 4492 Test Method for Analysis of Benzene by GasChromatographyD 4790 Terminology of Aromatic Hydrocarbons and Re-lated ChemicalsD 5211 Specification for Xylenes fo
9、r p-Xylene FeedstockD 6563 Test Method for Benzene, Toluene, Xylene (BTX)Concentrates Analysis by Gas ChromatographyD 6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conf
10、ormance 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 Precision of a Test MethodE 1510 Practice for Installing Fused Silica Open TubularCapilla
11、ry Columns in Gas Chromatographs1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and TheirDerivatives.Current edition approved Jan. 1, 2008.
12、 Published January 2008. Originallyapproved in 1966. Last previous edition approved in 2007 as D 2360 07.2For 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 standar
13、ds Document Summary page onthe ASTM website.1*A Summary of Changes 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.Copyright by ASTM Intl (all rights reserved); Thu Jul 10 21:33:55 EDT 2008D
14、ownloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.2.2 Other Document:OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120033. Terminology3.1 Definitions:3.1.1 For definition of terms used in this test method seeTerminology D 4790.4. Summary
15、of Test Method4.1 A known amount of an internal standard is added to thespecimen that is then introduced into a gas chromatograph(GC) equipped with a flame ionization detector (FID). Thepeak area of each impurity and the internal standard ismeasured and the amount of each impurity is calculated from
16、the ratio of the peak area of the internal standard versus thepeak area of the impurity. Purity by GC is calculated bysubtracting the sum of the impurities found from 100.00.Results are reported either in weight percent or volumepercent.5. Significance and Use5.1 The determination of hydrocarbon imp
17、urities containedin toluene and mixed xylenes used as chemical intermediatesand solvents is typically required. This test is suitable forsetting specifications and for use as an internal quality controltool where aromatic monocyclic hydrocarbons are produced orare used. This test method is applicabl
18、e for determining theimpurities from the aromatic hydrocarbon production process.Typical impurities are alkanes containing 1 to 10 carbon atoms,benzene, toluene, ethylbenzene (EB), xylenes, and aromatichydrocarbons containing nine carbon atoms.5.1.1 Refer to Test Methods D 3797, D 3798, and D 4492fo
19、r determining the purity of o-Xylene, p-Xylene, and benzene,respectively.5.1.2 Refer to Test Method D 6563 for 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 gaschromatogr
20、aphic analysis cannot determine absolute purity ifunknown or undetected components are contained within thematerial being examined.6. Interferences6.1 The internal standard chosen must be satisfactorilyresolved from any impurity and the product peak. A peak willbe satisfactorily resolved from a neig
21、hboring peak if thedistance from the valley to the baseline between the two peaksis not greater than 50 % of the peak height of the smaller of thetwo peaks.6.2 In some cases for mixed xylenes, it may be difficult toresolve benzene from the nonaromatic hydrocarbons andtherefore the concentrations are
22、 determined as a composite. Inthe event that the benzene concentration must be determined,an alternate method must be selected to ensure an accurateassessment of the benzene concentration.7. Apparatus7.1 Gas ChromatographAny instrument having a flameionization detector that can be operated at the co
23、nditions givenin Table 1. The system should have sufficient sensitivity toobtain a minimum peak height response for 10 mg/kgn-butylbenzene of twice the height of the signal to backgroundnoise.7.2 ColumnsBoth capillary and packed columns contain-ing a stationary phase of cross-linked polyethylene gly
24、col havebeen found satisfactory. The column must give satisfactoryresolution of the internal standard from the solvent and theimpurity peaks, and should be such that benzene is elutedbetween n-nonane and n-decane. Table 1 contains a descriptionof a column that has been found satisfactory.7.3 Recorde
25、rElectronic integration is recommended.7.4 Microsyringe, 10 and 50, and 500-L capacity.7.5 Volumetric Flask, 50-mL capacity.8. Reagents8.1 Purity of ReagentReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specificatio
26、ns of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.48.2 Carrier GasHelium is recommended. However, hy-drogen may be used. Carrier, makeup and detector gasesshould have 99.999 % minimum purity. Oxygen in carrier gasshould be less than
27、1 ppm; less than 0.5 ppm is preferred.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.4Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington
28、, 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 National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Instrum
29、ental ParametersDetector Flame ionizationColumn:Tubing fused silicaStationary phase crosslinked polyethylene glycolAFilm thickness, 0.25Length, m 60Diameter, mm 0.32 IDTemperatures:Injector, C 270Detector, C 300Oven:Initial, C 60Time 1, min 10Final, C 150Rate, C/min 5Time 2, min 10Carrier gas helium
30、Flow rate, mL/min 1.0Split ratio 100:1Sample size, L 1.0Analysis time, min 38Linear velocity 145C, cm/s 20APolyethylene glycol such as Carbowax 20 M available from most chromato-graphic suppliers, has been found suitable for this purpose.D2360082Copyright by ASTM Intl (all rights reserved); Thu Jul
31、10 21:33:55 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.Purify carrier, makeup and detector gases to remove oxygen,water, and hydrocarbons.8.3 Airzero grade or better. Purify air to remove hydro-carbons and water.8.4 High Purity p-
32、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-mately 3.8 L of material and cool in an explosion-proof freezerat 0 6 5C until appr
33、oximately12 to34 of the p-xylene hasfrozen. This should require about 5 h. Remove the sample anddecant the liquid portion. The solid portion is the purifiedp-xylene. Allow the p-xylene to thaw and repeat the crystalli-zation step on the remaining sample until the p-xylene is freeof contamination as
34、indicated by gas chromatography.8.5 Pure Compounds, for calibration, shall includen-nonane, benzene, toluene, ethylbenzene (EB), o-xylene andcumene. The purity of all reagents should be 99 weight %. Ifthe purity is less than 99 %, the concentration and identificationof impurities must be known so th
35、at the composition of thestandard can be adjusted for the presence of the impurities.8.5.1 Internal Standardn-butylbenzene (NBB) is the rec-ommended internal standard of choice, however, other com-pounds may be found acceptable provided they meet thecriteria as defined in Section 6.9. Hazards9.1 Con
36、sult current OSHA regulations, suppliers 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
37、the column into the chromatograph and adjustingthe instrument to the conditions described in Table 1 allowingsufficient time for the equipment to reach equilibrium. SeePractices E 260 and E 355 and E 1510 for additional informa-tion on gas chromatography practices and terminology.12. Calibration12.1
38、 Prepare a synthetic mixture of high purity p-xylenewith representative impurities. The volume of each hydrocar-bon impurity must be measured to the nearest 0.1 L and allliquid reference compounds must be brought to the sametemperature before mixing. Refer to Table 2 for an example ofa calibration b
39、lend. The nonaromatic fraction is represented byn-nonane, while o-xylene represents the xylene fraction.Cumene will represent the aromatic hydrocarbons containingnine carbon atoms or greater (C9aromatics).12.2 Using the exact volumes and densities in Table 2,calculate the weight percent concentratio
40、n for each impurity inthe calibration blend as follows:Ci5 Di!Vi!/Vp!Dp!100! (1)where:Di= density of impurity i from Table 2,Vi= volume of impurity i, mLs,Dp= density of p-xylene from Table 2,Vp= volume of p-xylene, mLs, andCi= concentration of impurity i, weight percent.12.3 Into a 50-mL volumetric
41、 flask, add 50.0 L ofn-butylbenzene (NBB) to 50.00 mLs of the calibration blendand mix well. Assuming a density of 0.857 for the calibrationblend and 0.856 for NBB, the resulting NBB concentration willbe 0.100 weight %, as determined from the equation in 12.2.12.3.1 All solutions and reference compo
42、unds must bebrought to the same temperature, preferably 25C, prior toadding the internal standard.12.4 Inject the resulting solution from 12.3 into the chro-matograph. A typical chromatogram is illustrated in Fig. 1.12.5 Determine the response factor for each impurity rela-tive to NBB by measuring t
43、he area under each peak andcalculate the relative response factor as follows:TABLE 2 Preparation of Calibration BlendCompound DensityARecommendedVolume (L)Resulting ConcentrationVolumePercentWeightPercentp-Xylene (see 8.4.1) 0.857 50.00 mL 99.72 99.72Benzene 0.874 10.0 0.020 0.020Toluene 0.862 10.0
44、0.020 0.020Ethylbenzene 0.863 50.0 0.100 0.101o-Xylene 0.876 50.0 0.100 0.102Cumene 0.857 10.0 0.020 0.020n-Nonane 0.714 10.0 0.020 0.017ADensity at 25C. Values obtained from Physical Constants of Hydrocarbons C1to C10, ASTM Publication Data Series 4A, 1971.FIG. 1 Typical Analysis of Calibration Sta
45、ndardD2360083Copyright by ASTM Intl (all rights reserved); Thu Jul 10 21:33:55 EDT 2008Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.RRFi5As!Ci!Cs!Ai!(2)where:RRFi= response factor for impurity i relative to the internalstandard,Ai= peak are
46、a of impurity, i,As= peak area of the internal standard, NBB,Cs= concentration of the internal standard, NBB,weight percent, andCi= concentration of impurity i, as calculated in 12.2,weight percent.12.6 Calculate the response factors to the nearest 0.001.13. Procedure13.1 Bring the internal standard
47、 and the sample to beanalyzed to identical temperatures, preferably 25C. Make surethat the temperature of the sample is consistent with that of thecalibration standard prepared in Section 12. Pipet 50.0 L ofinternal standard into a 50-mL volumetric flask containing50.00 mLs of sample. Mix well.13.2
48、Depending upon the actual chromatographs operatingconditions, inject an appropriate amount of sample into theinstrument. Make sure that the injection amount is consistentwith those conditions used to meet the criteria in 7.1.13.3 Measure the area of all peaks except the major com-ponent(s). Measurem
49、ents 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. Sum togetherall the C9aromatic peaks and report as a total area.13.4 Fig. 2 illustrates the analysis of Specification D 841toluene. Fig. 3 illustrates the analysis of Specification D 5211mixed xylenes.14. Calculation
