1、Designation: D7871 13Standard Test Method forAnalysis of Cyclohexane by Gas Chromatography (EffectiveCarbon Number)1This standard is issued under the fixed designation D7871; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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. Scope1.1 This test method covers the determination of the purityof cyclohexane by gas chromatography.1.2 This test method h
3、as been found applicable to themeasurement of impurities such as those found in Table 1,which are impurities that may be found in cyclohexane. Theimpurities can be analyzed over a range of 1 to 400 mg/kg bythis method, but may be applicable to a wider range.1.3 The limit of detection is 1 mg/kg.1.4
4、In determining the conformance of the test results usingthis test method to applicable specifications, results shall berounded off in accordance with the rounding-off method ofPractice E29.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in
5、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 limitations prior to use. F
6、or specific hazardsstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D3437 Practice for Sampling and Handling Liquid CyclicProductsD4790 Terminology of Aromatic Hydrocarbons and RelatedChemicalsD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbo
7、ns and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE355 Practice for Gas Chromatography Terms and Relation-shipsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1510 Practice for I
8、nstalling Fused Silica Open TubularCapillary Columns in Gas Chromatographs2.2 Other Standards:3OSHA Regualtions, 29 CFR paragraphs 1910.1000 and1910.12003. Terminology3.1 See Terminology D4790 for definitions of terms used inthis test method.4. Summary of Test Method4.1 The specimen to be analyzed i
9、s injected into a gaschromatograph equipped with a flame ionization detector (FID)and a capillary column. The peak area of each component ismeasured and adjusted using effective carbon number (ECN)4response factors. The concentration of each component iscalculated based on its relative percentages o
10、f total adjustedpeak area and normalized to 100.0000 %.5. Significance and Use5.1 This test method is suitable for setting specifications onthe materials referenced in Table 1 and for use as an internalquality control tool where cyclohexane is produced or is usedin a manufacturing process. It may al
11、so be used in developmentor research work involving cyclohexane.5.2 This test method is useful in determining the purity ofcyclohexane with normal impurities present. If extremely highboiling or unusual impurities are present in the cyclohexane,this test method would not necessarily detect them and
12、thepurity calculation would be erroneous.1This 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 June
13、 1, 2013. Published July 2013. DOI: 10.1520/D7871-13.2For 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.3Availab
14、le 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.4Scanlon, J. T. and Willis, D. E., “Calculation of Flame Ionization DetectorRelative Response Factors Using the Effective Carbon Concept,” Journa
15、l ofChromatographic Science, Vol. 23, August 1985, ppl. 333-339.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Apparatus6.1 Gas ChromatographAny instrument having a flameionization detector that can be operated at the conditions g
16、ivenin Table 2. The system should have sufficient sensitivity toobtain a minimum peak height response for 1 mg/kg benzeneof twice the height of the signal background noise.6.2 ColumnsThe choice of column is based on resolutionrequirements. Any column may be used that is capable ofresolving all signi
17、ficant impurities from cyclohexane. Thecolumn described in Table 2 has been used successfully.6.3 RecorderElectronic integration is required.6.4 InjectorThe specimen must be precisely and repeat-ably injected into the gas chromatograph.An automatic sampleinjection device is highly recommended. Manua
18、l injection maybe employed if the precision stated in Tables 48 can bereliably and consistently satisfied.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications
19、of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8. Hazards8
20、.1 Consult current OSHA regulations, suppliers MaterialSafety Data Sheets, and local regulations for all materials listedin this test method.9. Sampling and Handling9.1 Sample the material in accordance with Practice D3437.10. Preparation of Apparatus10.1 Follow manufacturers instructions for mounti
21、ng andconditioning the column into the chromatograph and adjustingthe instrument to the conditions described in Table 2 allowingsufficient time for the equipment to reach equilibrium. SeePractices E1510 and E355 for additional information on gaschromatography practices and terminology.11. Calibratio
22、n and Standardization11.1 Prior to implementation of the ECN method, a labora-tory should demonstrate that acceptable precision and bias canbe obtained using a synthetic mixture of known composition(calibration check sample). (Fig. 1)12. Procedure12.1 Bring the sample to room temperature.12.2 Check
23、the chromatography performance to make surethat the column is properly resolving peaks.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 f
24、or LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Impurities Known or Suggested to be Present inCommercial CyclohexaneC4(1) n-butane(2) isobuteneC5(3) n-pentane(4) isopenta
25、ne(5) cyclopentaneC6(6) n-hexane(7) 2-methylpentane(8) 3-methylpentane(9) methylcyclopentane(10) benzene(11) cyclohexene(12) 2,2-dimethylbutane(13) 2,3-dimethylbutaneC7(14) 3,3-dimethylpentane(15) 2,2-dimethylpentane(16) 2,3-dimethylpentane(17) 2,4-dimethylpentane(18) 1,1-dimethylcyclopentane(19) tr
26、ans-1,3-dimethylcyclopentane(20) trans-1,2-dimethylcyclopentane(21) cis-1,2-dimethylcyclopentane(22) 2,2-dimethylcyclopentane(23) 2,4-dimethylcyclopentane(24) cis-1,3-dimethylcyclopentane(25) ethylcyclopentane(26) methylcyclohexane(27) 3-ethylpentane(28) 3-methylhexane(29) 2-methylhexane(30) n-hepta
27、ne(31) tolueneC8(32) iso-octane(33) p-xyleneC9(34) isopropylcylohexaneTABLE 2 Instrumental ParametersDetector flame ionizationInjection Port capillary splitterColumn A:Tubing fused silicaStationary phase bonded and crosslinked100 % dimethylpolysiloxaneFilm thickness, m 0.5Length, m 100Diameter, mm 0
28、.25Temperatures:Injector, C 230Detector, C 250Oven, C 32 hold for 12 minRamp 1 = 8C/min to 64C,hold for 10 minRamp 2 = 10C/min to 200C,hold for 5 minCarrier gas HydrogenFlow rate, mls/min 3Split ratio 100:1Sample size, l 1.0D7871 132FIG. 1 Typical Chromatogram of Calibration Mixture Using Conditions
29、 in Table 2D7871 13312.3 Inject into the gas chromatograph an appropriateamount of sample as previously determined in accordance with6.1 and start the analysis.12.4 Obtain a chromatogram and peak integration report.13. Calculations13.1 Using the ECN weight response factors listed inTable 3, calculat
30、e the concentration of each component asfollows:Ci5 Ai3 Ri! 3 1,000,000 Ai3 Ri! (1)where:Ci= concentraion for component i, mg/kg,Ai= peak area of component i, andRi= ECN response factor for component i.13.2 Calculate the purity of cyclohexane as follows:Cyclohexane, weight percent =Ci 10,000 (2)wher
31、e Ciis mg/kg of cyclohexane.14. Report14.1 Report the individual impurities to the nearest mg/kg.14.2 Report the purity of cyclohexane to the nearest 0.01 wt%.15. Precision and Bias615.1 An ILS was conducted which included two laborato-ries analyzing six sample three times. Practice E691 wasfollowed
32、 for the design and analysis of the data; this ILS didnot meet Practice E691 minimum requirements of six labs, fourmaterials, and two replicates. The details are given in ASTMResearch Report: RR:D16-1046.15.2 Repeatability (r)Results should not be suspect unlessthey differ by more than shown in Tabl
33、es 4-8. Results differingby less than “r” have a 95 % probability of being correct.15.3 Reproducibility (R)Results submitted by two labsshould not be considered suspect unless they differ by morethan shown in Tables 4-8. Results differing by less than “R”have a 95 % probability of being correct.15.4
34、 BiasSince there is no accepted reference materialsuitable for determining the bias in this test method, bias hasnot been determined.15.5 The precision statement was determined through sta-tistical examination of 180 results, from two laboratories, on ablank and five samples. The following amounts o
35、f impuritieswere added to the samples:Sample 1mg/kgSample 2mg/kgSample 3mg/kgSample 4mg/kgSample 5mg/kghexane 199 159 100 50 10methylcyclopentane 150 119.9 75 37.5 7.5benzene 49.9 39.9 25 12.5 2.5methycyclohexane 201 160 100 50 1016. Quality Guidelines16.1 Laboratories shall have a quality control s
36、ystem inplace.16.1.1 Confirm the performance of the test instrument ortest method by analyzing a quality control sample followingthe guidelines of standard statistical quality control practices.16.1.2 A quality control sample is a stable material isolatedfrom the production process and representativ
37、e of the samplebeing analyzed.16.1.3 When QA/QC protocols are already established inthe testing facility, these protocols are acceptable when theyconfirm the validity of test results.16.1.4 When there are no QA/QC protocols established inthe testing facility, use the guidelines described in GuideD68
38、09 or similar statistical quality control practices.17. Keywords17.1 analysis by gas chromatography; benzene;cyclohexane6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D16-1046. ContactASTM CustomerService at serviceastm.org.TAB
39、LE 3 Effective Carbon Number Response FactorsComponent Response Factor (Weight)Abenzene 0.91butane 1.015cyclohexane 0.98cyclopentane 0.982-methylpentane 1.0033-methylpentane 1.0032,2-dimethylpentane 1.002,3-dimethylpentane 1.002,4-dimethylpentane 1.002,2-demethylbutane 1.0032,3-dimethylbutane 1.0031
40、,1-dimethylcyclopentane 0.983-ethylpentane 0.98hexane 1.003methylcyclopentane 0.982-methylhexane 1.00n-pentane 1.008toluene 0.92o-xylene 0.9275m,p-xylene 0.9275unidentified peaks 1.000AResponse factors are relative to n-heptane.D7871 134TABLE 4 Methylcyclopentane (mg/kg)MaterialAverageARepeatability
41、LimitReproducibilityLimitXrRBlank 86 2 2Sample 1 232 3 3Sample 2 202 3 3Sample 3 159 2 2Sample 4 123 2 2Sample 5 93 4 4AThe average of the laboratories calculated averages.TABLE 5 Benzene (mg/kg)MaterialAverageARepeatabilityLimitReproducibilityLimitXrRBlank 0 0.9 0.9Sample 1 50 2 2Sample 2 40 2 2Sam
42、ple 3 26 2 2Sample 4 13 2 2Sample 5 4 0.5 1AThe average of the laboratories calculated averages.TABLE 6 Methylcyclohexane (mg/kg)MaterialAverageARepeatability Limit ReproducibilityLimitXrRBlank 85 3 22Sample 1 290 8 44Sample 2 249 10 42Sample 3 188 3 36Sample 4 136 4 27Sample 5 95 4 23AThe average o
43、f the laboratories calculated averages.TABLE 7 Hexane (mg/kg)MaterialAverageARepeatabilityLimitReproducibilityLimitXrRBlank 205 5 7Sample 1 403 8 9Sample 2 362 7 7Sample 3 303 2 4Sample 4 255 7 7Sample 5 215 7 7AThe average of the laboratories calculated averages.D7871 135ASTM International takes no
44、 position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own respons
45、ibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed t
46、o ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the add
47、ress shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone),
48、 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).TABLE 8 Cyclohexane (wt %)MaterialAverageARepeatabilityLimitReproducibilityLimitXrRBlank 99.939 0.001 0.009Sample 1 98.879 0.001 0.012Sample 2 99.891 0.004 0.011Sample 3 99.908 0.001 0.009Sample 4 99.923 0.002 0.010Sample 5 99.935 0.001 0.009AThe average of the laboratories calculated averages.D7871 136
