1、Designation: D5713 09Standard Test Method forAnalysis of High Purity Benzene for Cyclohexane Feedstockby Capillary Gas Chromatography1This standard is issued under the fixed designation D5713; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 specificimpurities in, and the purity of benzene f
3、or cyclohexanefeedstock by gas chromatography.1.2 This test method has been found applicable to benzenein the range from 99 to 100 % purity and to impurities atconcentrations of 2 to 10 000 mg/kg.1.3 In determining the conformance of the test results usingthis method to applicable specifications, re
4、sults shall berounded off in accordance with the rounding-off method ofPractice E29.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated
5、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 limitations prior to use. For a specifichazard statement, see 7.1 and Section 8.2. Referenced Documents2.1 ASTM Standards:2D3437 Pra
6、ctice for Sampling and Handling Liquid CyclicProductsD4790 Terminology ofAromatic Hydrocarbons and RelatedChemicalsD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Confor
7、mance with SpecificationsE260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and Rela-tionshipsE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs2.2 Other Document:OSHA Regulations, 29 CFR paragraphs 1910.1000 and19
8、10.120033. Terminology3.1 Definitions:3.1.1 SeeTerminology D4790 for definition of terms used inthis test method.4. Summary of Test Method4.1 In this test method, the chromatogram peak area for eachimpurity is compared to the peak area of the internal standard(n-octane or other suitable known) added
9、 to the sample. Fromthe response factor of toluene relative to that of the internalstandard, and using a response factor of 1.00 for nonaromaticimpurities and the amount of internal standard added, theconcentrations of the impurities are calculated. The benzenecontent is obtained by subtracting the
10、total amount of allimpurities from 100.00.5. Significance and Use5.1 This test method is useful for benzene purity on thebasis of impurities normally present in benzene and may beused for final product inspections and process control.5.2 This test method will detect the following impurities:toluene,
11、 methylcyclopentane, n-hexane, 2-methylhexane, cy-clohexane, cyclopentane, 2-methylpentane, 2,3-dimethylpentane, 3-methylhexane, n-heptane, methylcyclohex-ane, ethylcyclopentane, 2,4-dimethylhexane, trimethylpentane,and others where specific impurity standards are available.Absolute purity cannot be
12、 accurately determined if unknownimpurities are present.6. Apparatus6.1 Gas ChromatographAny gas chromatograph having atemperature programmable oven, flame ionization detector and1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is th
13、e direct responsibility ofSubcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and TheirDerivatives.Current edition approved Dec. 1, 2009. Published January 2010. Originallyapproved in 1995. Last previous edition approved in 2005 as D5713 05. DOI:10.1520/D5713-09.2For referenced ASTM standa
14、rds, 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.3Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capit
15、ol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.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.a splitter injector suitable for use with a
16、fused silica capillarycolumn may be used, provided the system has sufficientsensitivity that will give a minimum peak height of 3 times thebackground noise for 2 mg/kg of an impurity.6.2 ColumnFused silica capillary columns have beenfound to be satisfactory.An example is 50 m of 0.20-mm insidediamet
17、er fused silica capillary internally coated to a filmthickness of 0.50 m with polydimethylsiloxane (see Table 1for suggested instrument parameters). Other columns may beused after it has been established that such a column is capableof separating all major impurities (for example, compoundslisted in
18、 5.2) and the internal standard from the benzene underoperating conditions appropriate for the column. The columnmust give satisfactory resolution (distance from the valleybetween the peaks is not greater than 50 % of the peak heightsof the impurity) of cyclohexane from benzene as well as otherimpur
19、ity peaks. A poorly resolved peak, such as cyclohexane,will often require a tangent skim from the neighboring peak.6.3 Electronic Integration, with tangent skim capabilities isrecommended.6.4 Vial.6.5 Microsyringes, assorted volumes.6.6 Injector, the specimen must be precisely and repeatedlyinjected
20、 into the gas chromatograph. An automatic sampleinjection device is highly recommended. Manual injection canbe employed if the precision stated in Table 2, IntermediatePrecision and Reproducibility, can be reliably and consistentlysatisfied.7. Reagents and Materials7.1 Carrier Gasa carrier gas (99.9
21、99 % minimum purity)appropriate to the type of detector used should be employed.(WarningIf hydrogen is used as the carrier gas, take specialsafety precautions to ensure that the system is free of leaks andthat the effluent is properly vented or burned.)7.2 Hydrogen, for the flame ionization detector
22、 (FID) mini-mum purity of 99.999 % and 0.5 ppm total hydrocarbons ispreferred.7.3 Air, for the flame ionization detector, 0.1 ppm totalhydrocarbons is preferred.7.4 n-octane, 99.0 % minimum purity, or other internalstandard (99.0 % minimum purity), such as iso-octane, previ-ously analyzed to be free
23、 of compounds coeluting withimpurities in the sample.NOTE 1It is highly recommended the carrier, make-up and detectorgases be purified to remove oxygen (to less than 1 ppm, less than 0.5 ppmis preferred), water and hydrocarbons. It is also recommended the air bepurified to remove hydrocarbons and wa
24、ter.8. Hazards8.1 Consult current OSHA regulations, suppliers MaterialSafety Data Sheets, and local regulations for all materials usedin this test method.9. Sampling9.1 Sample in accordance with Practice D3437.10. Preparation of Apparatus10.1 Follow the manufacturers instructions for mountingthe col
25、umn into the chromatograph and adjusting the instru-ment to the desired conditions. Allow sufficient time for theequipment to reach equilibrium. See Practices E260, E355 andE1510 for additional information on gas chromatographyprocedures, terminology, and column installation. The columnand condition
26、s in Table 1 were used to develop this analysis. Ifthere is a dispute, the column and conditions should be agreedupon between the parties or use Table 1 as a referee.11. Procedure11.1 Transfer approximately 10 g of the sample to beanalyzed to a tared vial and weigh to the nearest 0.1 mg. (MakeTABLE
27、1 Instrument Typical ParametersCarrier gas hydrogenLinear velocity at 40C, cm/s 40Detector flame ionizationDetector temperature, C 250CInjection port temperature, C 250CSplit ratio 40:1Split flow, mL/min 60Column 50mby0.20mmIDby0.5mbonded polydimethylsiloxanecapillary columnInitial column temperatur
28、e, C 40Initial time, min 17Programming rate 10C/minFinal temperature, C 250CFinal time, min 10Sample size, L 1.2TABLE 2 Intermediate Precision and ReproducibilityComponentAverageConcentration ppmWeight %IntermediatePrecisionReproducibilityBenzene 99.9699.9799.960.0060.0070.0080.0220.0200.025Methylcy
29、clopentane 10443548.312.22.527.919.415.1Toluene 6463285.13.01.822.016.69.1Methylcyclohexane 13243797.41.43.234.85.417.0Methylcyclohexane + 196 7.9 54.9Toluene 10610612.94.433.620.4n-Hexane 4322.21.51.83.72.22.5n-Heptane 616152.71.54.011.15.623.4Ethylcyclopentane 76111.81.91.53.711.06.1Total Other Im
30、purities 9910718522.544.655.5163.0190.6233.0D5713 092sure that the sample is deposited in the center of the vial so thatthe liquid does not contact the neck.)11.2 Add approximately 0.1 g of internal standard (noctanewas used in Fig. 1) and quickly reweigh to the nearest 0.1 mg.(The internal standard
31、 is added to the vial while on the balancepan and deposited into the center of the liquidnot on the sideof the vial.)11.3 Cap the mixture and mix by inverting several times.11.4 Inject into the gas chromatograph an appropriateamount of the mixture as previously determined in accordancewith 6.1 and 6
32、.2 and immediately start the analysis. (1.2 Lwas used in Fig. 1.)11.5 Determine the areas of all the impurity peaks and theinternal standard. Identify the specific impurities by comparingthe chromatogram obtained to a typical chromatogram. (Uni-dentified impurities are summed and reported as a compo
33、site.)The chromatogram shown in Fig. 1 can be used for the columnand conditions specified in Table 1.12. Calculation12.1 Measure the areas of all peaks, including the internalstandard, except the benzene peak.12.2 Calculate the weight to milligram per kilogrammg/kg of the individual impurities, Cias
34、 follows:Ci5 106BDFGH(1)where:B = peak area of a specific impurity or group of impuri-tiesD = response factor, (see 12.3)F = mass of internal standard added to the sample, gG = peak area of the internal standardH = weight of sample before addition of internal stan-dard, g106= factor to convert to we
35、ight-mg/kg12.3 A response factor of 1.000 should be used for allhydrocarbon impurities except toluene which will be 0.935.12.4 Calculate the benzene content by subtracting the sumof the impurities from 100.000. Benzene weight% = 100.000 (sum of impurities in weight %). Total impuri-ties are converte
36、d from mg/kg to weight percent by multiplyingby 0.0001 %.13. Report13.1 Report the concentration of impurities to the nearestmg/kg and the benzene content to the nearest 0.01 %. Forconversion purposes, 1 mg/kg equals 0.0001 %.FIG. 1 High Purity BenzeneTypical Chromatogram(See Table 1)D5713 09314. Pr
37、ecision and Bias414.1 PrecisionThe following criteria should be used tojudge the acceptability (95 % probability level) of resultsobtained by this test method. The criteria in Table 2 werederived from an interlaboratory study between six laboratories.Three samples were analyzed in duplicate on two d
38、ays.14.1.1 Intermediate Precision (formerly Repeatability)Results in the same laboratory should not be consideredsuspect unless they differ by more than the amounts shown inTable 2. On the basis of test error alone, the difference betweentwo results obtained in the same laboratory on the samemateria
39、l will be expected to exceed this value only 5 % of thetime.14.1.2 ReproducibilityResults submitted by each of twolaboratories should not be considered suspect unless they differby more than the amount shown in Table 2. On the basis of testerror alone, the difference between two test results obtaine
40、d indifferent laboratories on the same material will be expected toexceed this value only 5 % of the time.14.2 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod for measuring specific impurities, bias has not beendetermined.15. Qu
41、ality Guidelines15.1 Confirm the performance of the test instrument or testmethod by analyzing a quality control sample following theguidelines of standard statistical quality control practices.15.2 A quality control sample is a stable material isolatedfrom the production process and representative
42、of the samplebeing analyzed.15.3 When QA/QC protocols are already established in thetesting facility, these protocols are acceptable when theyconfirm the validity of test results.15.4 When there are no QA/QC protocols established in thetesting facility, use the guidelines described in Guide D6809 or
43、similar statistical quality control practices.16. Keywords16.1 benzene; cyclohexane feedstock; impuritiesSUMMARY OF CHANGESCommittee D16 has identified the location of selected changes to this standard since the last issue(D5713 05) that may impact the use of this standard. (Approved December 1, 200
44、9.)(1) Modified wording in 3.1.1 to reflect D16 Editorial Guide-lines dated June 25, 2009.(2) Modified wording in footnotes 1 and 3 to reflect D16Editorial Guidelines dated June 25, 2009.(3) Modified wording in 5.1 to reflect D16 Editorial Guide-lines dated June 25, 2009.(4) Changed carrier gas puri
45、ty in 7.1 from “minimum purity of99.95 % mol” to “99.999 % minimum purity.”(5) Modified wording in Section 7, Note 1 to reflect D16Editorial Guidelines dated June 25, 2009.(6) Revised Section 15, Quality Guidelines, to reflect D16Editorial Guidelines dated June 25, 2009.(7) Corrected spelling of wor
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