1、Designation: D7871 13D7871 18Standard 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,
2、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 Scope*1.1 This test method covers the determination of the purity of cyclohexane by gas chromatography.1.2 Th
3、is test method has been found applicable to the measurement of impurities such as those found in Table 1, which areimpurities that may be found in cyclohexane. The impurities can be analyzed over a range of 1 to 400 mg/kg by this method, butmay be applicable to a wider range.1.3 The limit of detecti
4、on is 1 mg/kg.1.4 In determining the conformance of the test results using this test method to applicable specifications, results shall be roundedoff in accordance with the rounding-off method of Practice E29.1.5 The values stated in SI units are to be regarded as standard. No other units of measure
5、ment are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplic
6、ability of regulatory limitations prior to use. For specific hazards statements, see Section 8.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Stand
7、ards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D3437 Practice for Sampling and Handling Liquid Cyclic ProductsD4790 Terminology of Aromatic Hydrocarbons and Related ChemicalsD6809 Guide for
8、 Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related MaterialsE29 Practice for Using Significant Digits in Test Data to Determine Conformance with SpecificationsE355 Practice for Gas Chromatography Terms and RelationshipsE691 Practice for Conducting an Interlaborat
9、ory Study to Determine the Precision of a Test MethodE1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs2.2 Other Standards:3OSHA Regualtions,Regulations, 29 CFR paragraphs 1910.1000 and 1910.12003. Terminology3.1 See Terminology D4790 for definitions of t
10、erms used in this test method.1 This test method is under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons Aromatic, Industrial, Specialty and Related Chemicals and is the directresponsibility of Subcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Their Derivatives.Curre
11、nt edition approved June 1, 2013Jan. 1, 2018. Published July 2013January 2018. Originally approved in 2013. Last previous edition approved in 2013 as D7871 13. DOI: 10.1520/D7871-13.10.1520/D7871-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service
12、at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standardsstandards Document Summary page on the ASTM website.3 Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.acc
13、ess.gpo.gov.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consu
14、lt prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
15、PA 19428-2959. United States14. Summary of Test Method4.1 The specimen to be analyzed is injected into a gas chromatograph equipped with a flame ionization detector (FID) and acapillary column. The peak area of each component is measured and adjusted using effective carbon number (ECN)4 responsefact
16、ors. The concentration of each component is calculated based on its relative percentages of total adjusted peak area andnormalized to 100.0000 %.5. Significance and Use5.1 This test method is suitable for setting specifications on the materials referenced in Table 1 and for use as an internal qualit
17、ycontrol tool where cyclohexane is produced or is used in a manufacturing process. It may also be used in development or researchwork involving cyclohexane.5.2 This test method is useful in determining the purity of cyclohexane with normal impurities present. If extremely high boilingor unusual impu
18、rities are present in the cyclohexane, this test method would not necessarily detect them and the purity calculationwould be erroneous.6. Apparatus6.1 Gas ChromatographAny instrument having a flame ionization detector that can be operated at the conditions given inTable 2. The system should have suf
19、ficient sensitivity to obtain a minimum peak height response for 1 mg/kg benzene of twicethe height of the signal background noise.6.2 ColumnsThe choice of column is based on resolution requirements.Any column may be used that is capable of resolvingall significant impurities from cyclohexane. The c
20、olumn described in Table 2 has been used successfully.4 Scanlon, J. T. and Willis, D. E., “Calculation of Flame Ionization Detector Relative Response Factors Using the Effective Carbon Concept,” Journal of ChromatographicScience, Vol. 23, August 1985, ppl. 333-339.TABLE 1 Impurities Known or Suggest
21、ed to be Present inCommercial CyclohexaneC4(1) n-butane(2) isobuteneC5(3) n-pentane(4) isopentane(5) cyclopentaneC6(6) n-hexane(7) 2-methylpentane(8) 3-methylpentane(9) methylcyclopentane(10) benzene(11) cyclohexene(11) cyclohexane(12) 2,2-dimethylbutane(13) 2,3-dimethylbutaneC7(14) 3,3-dimethylpent
22、ane(15) 2,2-dimethylpentane(16) 2,3-dimethylpentane(17) 2,4-dimethylpentane(18) 1,1-dimethylcyclopentane(19) trans-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(2
23、5) ethylcyclopentane(26) methylcyclohexane(27) 3-ethylpentane(28) 3-methylhexane(29) 2-methylhexane(30) n-heptane(31) tolueneC8(32) iso-octane(33) p-xyleneC9(34) isopropylcylohexaneD7871 1826.3 RecorderElectronic integration is required.6.4 InjectorThe specimen must be precisely and repeatably injec
24、ted into the gas chromatograph. An automatic sampleinjection device is highly recommended. Manual injection may be employed if the precision stated in Tables 48 can be reliablyand consistently satisfied.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests
25、. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.5 Other grades may be used, provided it is first ascertained that the reagent is of suffi
26、ciently highpurity to permit its use without lessening the accuracy of the determination.8. Hazards8.1 Consult current OSHA regulations, suppliers Material Safety Data Sheets, and local regulations for all materials listed inthis test method.9. Sampling and Handling9.1 Sample the material in accorda
27、nce with Practice D3437.10. Preparation of Apparatus10.1 Follow manufacturersmanufacturers instructions for mounting and conditioning the column into the chromatograph andadjusting the instrument to the conditions described in Table 2 allowing sufficient time for the equipment to reach equilibrium.
28、SeePractices E1510 and E355 for additional information on gas chromatography practices and terminology.11. Calibration and Standardization11.1 Prior to implementation of the ECN method, a laboratory should demonstrate that acceptable precision and bias can beobtained using a synthetic mixture of kno
29、wn composition (calibration check sample). (Fig. 1)12. Procedure12.1 Bring the sample to room temperature.12.2 Check the chromatography performance to make sure that the column is properly resolving peaks.12.3 Inject into the gas chromatograph an appropriate amount of sample as previously determined
30、 in accordance with 6.1 andstart the analysis.12.4 Obtain a chromatogram and peak integration report.5 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see An
31、alar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.TABLE 2 Instrumental ParametersDetector flame ionizationInjection Port capillary splitterColumn A:Tubing fused s
32、ilicaStationary phase bonded and crosslinked100 % dimethylpolysiloxaneFilm thickness, m 0.5Length, m 100Diameter, mm 0.25Temperatures: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, ml
33、s/min 3Split ratio 100:1Sample size, l 1.0D7871 183FIG. 1 Typical Chromatogram of Calibration Mixture Using Conditions in Table 2D7871 18413. Calculations13.1 Using the ECN weight response factors listed inTable 3, calculate the concentration of each component as follows:Ci 5 Ai 3 Ri! 3 1,000,000 Ai
34、 3 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)where Ci is mg/kg of cyclohexane.14. Report14.1 Report the individual impu
35、rities to the nearest mg/kg.14.2 Report the purity of cyclohexane to the nearest 0.01 wt %.TABLE 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
36、-dimethylpentane 1.002,4-dimethylpentane 1.002,2-demethylbutane 1.0032,3-dimethylbutane 1.0031,1-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 1.000TABLE 3 Effective Carb
37、on Number Response FactorsComponent Response Factor (Weight)Abenzene 0.9095butane 1.0151cyclohexane 0.9799cyclopentane 0.97992-methylpentane 1.00343-methylpentane 1.00342,2-dimethylpentane 1.00002,3-dimethylpentane 1.00002,4-dimethylpentane 1.00002,2-dimethylbutane 1.00342,3-dimethylbutane 1.00341,1
38、-dimethylcyclopentane 0.97993-ethylpentane 0.9799hexane 1.0034methylcyclopentane 0.97992-methylhexane 1.0000n-pentane 1.0080toluene 0.9195o-xylene 0.9271m,p-xylene 0.9271unidentified peaks 1.0000A Response factors are relative to n-heptane.D7871 18515. Precision and Bias615.1 An ILS was conducted wh
39、ich included two laboratories analyzing six sample three times. Practice E691 was followed forthe design and analysis of the data; this ILS did not meet Practice E691 minimum requirements of six labs, four materials, andtwo replicates. The details are given in ASTM Research Report: RR:D16-1046.15.2
40、Repeatability (r)Results should not be suspect unless they differ by more than shown in Tables 4-8. Results differing byless than “r” have a 95 % probability of being correct.15.3 Reproducibility (R)Results submitted by two labs should not be considered suspect unless they differ by more thanshown i
41、n Tables 4-8. Results differing by less than “R” have a 95 % probability of being correct.15.4 BiasSince there is no accepted reference material suitable for determining the bias in this test method, bias has not beendetermined.15.5 The precision statement was determined through statistical examinat
42、ion of 180 results, from two laboratories, on a blankand five samples. The following amounts of impurities were 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 2.5methycycl
43、ohexane 201 160 100 50 10methylcyclohexane 201 160 100 50 1016. Quality Guidelines16.1 Laboratories shall have a quality control system in place.16.1.1 Confirm the performance of the test instrument or test method by analyzing a quality control sample following theguidelines of standard statistical
44、quality control practices.16.1.2 Aquality control sample is a stable material isolated from the production process and representative of the sample beinganalyzed.16.1.3 When QA/QC protocols are already established in the testing facility, these protocols are acceptable when they confirmthe validity
45、of test results.16.1.4 When there are no QA/QC protocols established in the testing facility, use the guidelines described in Guide D6809 orsimilar statistical quality control practices.17. Keywords17.1 analysis by gas chromatography; benzene; cyclohexane6 Supporting data have been filed at ASTM Int
46、ernational Headquarters and may be obtained by requesting Research Report RR:D16-1046. Contact ASTM CustomerService at serviceastm.org.TABLE 4 Methylcyclopentane (mg/kg)Material AverageARepeatabilityLimitReproducibilityLimitX r RBlank 86 2 2Sample 1 232 3 3Sample 2 202 3 3Sample 3 159 2 2Sample 4 12
47、3 2 2Sample 5 93 4 4A The average of the laboratories calculated averages.D7871 186TABLE 5 Benzene (mg/kg)Material AverageARepeatabilityLimitReproducibilityLimitX r RBlank 0 0.9 0.9Sample 1 50 2 2Sample 2 40 2 2Sample 3 26 2 2Sample 4 13 2 2Sample 5 4 0.5 1A The average of the laboratories calculate
48、d averages.TABLE 6 Methylcyclohexane (mg/kg)Material AverageARepeatability Limit ReproducibilityLimitX r RBlank 85 3 22Sample 1 290 8 44Sample 2 249 10 42Sample 3 188 3 36Sample 4 136 4 27Sample 5 95 4 23A The average of the laboratories calculated averages.TABLE 7 Hexane (mg/kg)Material AverageARep
49、eatabilityLimitReproducibilityLimitX r RBlank 205 5 7Sample 1 403 8 9Sample 2 362 7 7Sample 3 303 2 4Sample 4 255 7 7Sample 5 215 7 7A The average of the laboratories calculated averages.TABLE 8 Cyclohexane (wt %)Material AverageARepeatabilityLimitReproducibilityLimitX r RBlank 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 0.009A The average of the laboratories calculated averages.D7871 187SUMMARY OF CHANGESCommittee D16 has identifi
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