1、Designation: D5713 09D5713 14Standard 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
2、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 specific impurities in, and the purity of
3、benzene for cyclohexane feedstock bygas chromatography.1.2 This test method has been found applicable to benzene in 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 using this method to applicable specifi
4、cations, results shall be roundedoff in accordance with the rounding-off method of Practice E29.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if a
5、ny, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For a specific hazard statement,statements, see 7.17.2 and Section 8.2. Referenced Documents2.
6、1 ASTM Standards:2D3437 Practice for Sampling and Handling Liquid Cyclic ProductsD4790 Terminology of Aromatic Hydrocarbons and Related ChemicalsD6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related MaterialsE29 Practice for Using Significant Digits i
7、n Test Data to Determine Conformance with SpecificationsE260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and RelationshipsE1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs2.2 Other Document:OSHA Regulations, 29
8、 CFR paragraphs 1910.1000 and 1910.120033. Terminology3.1 Definitions:3.1.1 See Terminology D4790 for definition of terms used in this test method.4. Summary of Test Method4.1 In this test method, the chromatogram peak area for each impurity is compared to the peak area of the internal standard(n-oc
9、tane or other suitable known) added to the sample. From the response factor of toluene relative to that of the internal standard,and using a response factor of 1.00 for nonaromatic impurities and the amount of internal standard added, the concentrations ofthe impurities are calculated. The benzene c
10、ontent is obtained by subtracting the total amount of all impurities from 100.00.1 This test method is under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of SubcommitteeD16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Thei
11、r Derivatives.Current edition approved Dec. 1, 2009Feb. 15, 2014. Published January 2010March 2014. Originally approved in 1995. Last previous edition approved in 20052009 asD5713 05.D5713 09. DOI: 10.1520/D5713-09.10.1520/D5713-14.2 For referencedASTM standards, visit theASTM website, www.astm.org,
12、 or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards 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,
13、 DC 20401, http:/www.access.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 rec
14、ommends that users consult 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 C
15、700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 This test method is useful for benzene purity on the basis of impurities normally present in benzene and may be used forfinal product inspections and process control.5.2 This test method will detect the following impurit
16、ies: toluene, methylcyclopentane, n-hexane, 2-methylhexane,cyclohexane, cyclopentane, 2-methylpentane, 2,3-dimethylpentane, 3-methylhexane, n-heptane, methylcyclohexane,ethylcyclopentane, 2,4-dimethylhexane, trimethylpentane, and others where specific impurity standards are available. Absolutepurity
17、 cannot be accurately determined if unknown impurities are present.6. Apparatus6.1 Gas ChromatographAny gas chromatograph having a temperature programmable oven, flame ionization detector and asplitter injector suitable for use with a fused silica capillary column may be used, provided the system ha
18、s sufficient sensitivity thatwill give a minimum peak height of 3 times the background noise for 2 mg/kg of an impurity.6.2 ColumnFused silica capillary columns have been found to be satisfactory.An example is 50 m of 0.20-mm inside diameterfused silica capillary internally coated to a film thicknes
19、s of 0.50 m with polydimethylsiloxane (see Table 1 for suggestedinstrument parameters). Other columns may be used after it has been established that such a column is capable of separating allmajor impurities (for example, compounds listed in 5.2) and the internal standard from the benzene under oper
20、ating conditionsappropriate for the column. The column must give satisfactory resolution (distance from the valley between the peaks is not greaterthan 50 % of the peak heights of the impurity) of cyclohexane from benzene as well as other impurity peaks. A poorly resolvedpeak, such as cyclohexane, w
21、ill often require a tangent skim from the neighboring peak.6.3 Electronic Integration, with tangent skim capabilities is recommended.6.4 Vial.6.5 Microsyringes, assorted volumes.6.6 Injector, the specimen must be precisely and repeatedly injected into the gas chromatograph.An automatic sample inject
22、iondevice is highly recommended. Manual injection can be employed if the precision stated in Table 2, Intermediate Precision andReproducibility, can be reliably and consistently satisfied.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherw
23、ise indicated it is intended that allreagents shall conform to the specifications of the Committee onAnalytical reagents of theAmerican Chemical Society, where suchspecifications are available.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purit
24、yto permit its use without lessening the accuracy of the determination.7.2 Carrier Gasa carrier gas (99.999 % minimum purity) appropriate to the type of detector used should be employed.(WarningIf hydrogen is used as the carrier gas, take special safety precautions to ensure that the system is free
25、of leaks and thatthe effluent is properly vented or burned.)4 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 Analar Standards for Laboratory Chemicals,
26、BHD, Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.TABLE 1 Instrument Typical Parameters RecommendedOperating ConditionsCarrier gas hydrogenLinear velocity at 40C, cm/s 40Detector flame ionizationDetect
27、or temperature, C 250CInjection port temperature, C 250CSplit ratio 40:1Split flow, mL/min 60Column 50 m by 0.20 mm ID by 0.5 mbonded polydimethylsiloxanecapillary columnInitial column temperature, C 40Initial time, min 17Programming rate 10C/minFinal temperature, C 250CFinal time, min 10Sample size
28、, L 1.2D5713 1427.3 Hydrogen, for the flame ionization detector (FID) minimum purity of 99.999 % and 0.5 ppm total hydrocarbons ispreferred.7.4 Air, for the flame ionization detector, 0.1 ppm total hydrocarbons is preferred.7.5 n-octane, 99.0 % minimum purity, or other internal standard (99.0 % mini
29、mum purity), such as iso-octane, previouslyanalyzed to be free of compounds coeluting with impurities in the sample.TABLE 2 Intermediate Precision and Reproducibility Summaryof Precision DataComponentAverageAverageConcentration ppmWeight %mg/kgIntermediatePrecisionPrecisionReproducibilityBenzene (we
30、ight %) 99.9699.9799.960.0060.0070.0080.0220.0200.025Methylcyclopentane 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
31、.623.4Ethylcyclopentane 76111.81.91.53.711.06.1Total Other Impurities 9910718522.544.655.5163.0190.6233.0D5713 143NOTE 1It is highly recommended the carrier, make-up and detector gases be purified to remove oxygen (to less than 1 ppm, less than 0.5 ppm ispreferred), water and hydrocarbons. It is als
32、o recommended the air be purified to remove hydrocarbons and water.8. Hazards8.1 Consult current OSHA regulations, supplierssuppliers Material Safety Data Sheets, and local regulations for all materialsused in this test method.9. Sampling9.1 Sample in accordance with Practice D3437.10. Preparation o
33、f Apparatus10.1 Follow the manufacturers instructions for mounting and conditioning the column into the chromatograph and adjustingthe instrument to the desired conditions. Allow sufficient time for the equipment to reach equilibrium. See Practices E260, E355and E1510 for additional information on g
34、as chromatography procedures, terminology, and column installation. The column andconditions in Table 1 were used to develop this analysis. If there is a dispute, the column and conditions should be agreed uponbetween the parties or use Table 1 as a referee.11. Procedure11.1 Transfer approximately 1
35、0 g of the sample to be analyzed to a tared vial and weigh to the nearest 0.1 mg. (Make sure thatthe sample is deposited in the center of the vial so that the liquid does not contact the neck.)FIG. 1 High Purity BenzeneTypical Chromatogram(See Table 1) for Operating Conditions)D5713 14411.2 Add appr
36、oximately 0.1 g of internal standard (noctane was used in Fig. 1) and quickly reweigh to the nearest 0.1 mg. (Theinternal standard is added to the vial while on the balance pan and deposited into the center of the liquidnot on the side of thevial.)11.3 Cap the mixture and mix by inverting several ti
37、mes.11.4 Inject into the gas chromatograph an appropriate amount of the mixture as previously determined in accordance with 6.1and 6.2 and immediately start the analysis. (1.2 L was used in Fig. 1.)11.5 Determine the areas of all the impurity peaks and the internal standard. Identify the specific im
38、purities by comparing thechromatogram obtained to a typical chromatogram. (Unidentified impurities are summed and reported as a composite.) Thechromatogram shown in Fig. 1 can be used for the column and conditions specified in Table 1.12. Calculation12.1 Measure the areas of all peaks, including the
39、 internal standard, except the benzene peak.12.2 Calculate the weight to milligram per kilogrammg/kg of the individual impurities, Ci as follows:D5713 145Ci 5106 BDFGH (1)where:B = peak area of a specific impurity or group of impuritiesD = response factor, (see 12.3)F = mass of internal standard add
40、ed to the sample, gG = peak area of the internal standardH = weight of sample before addition of internal standard, g106 = factor to convert to weight-mg/kgwhere:B = peak area of a specific impurity or group of impuritiesD = response factor, (see 12.3)F = mass of internal standard added to the sampl
41、e, gG = peak area of the internal standardH = weight of sample before addition of internal standard, g106 = factor to convert to weight-mg/kg12.3 A response factor of 1.000 should be used for all hydrocarbon impurities except toluene which will be 0.935.12.4 Calculate the benzene content by subtract
42、ing the sum of the impurities from 100.000. Benzene weight % = 100.000 (sumof impurities in weight %). Total impurities are converted from mg/kg to weight percent by multiplying by 0.0001 %.13. Report13.1 Report the concentration of impurities to the nearest mg/kg and the benzene content to the near
43、est 0.01 %. For conversionpurposes, 1 mg/kg equals 0.0001 %.14. Precision and Bias514.1 PrecisionThe following criteria in Table 2 should be used to judge the acceptability (95 % probability level) of at the95 % probability level of the results obtained by this test method. method (95 % confidence l
44、evel). The criteria in Table 2werederived from an interlaboratory study between six laboratories. Three samples were of three samples analyzed in duplicate on twodays.days between six laboratories. Details of the design and analysis of the data is given in ASTM Research Report RR:RR:D16-1018.14.1.1
45、Intermediate Precision (formerly Repeatability)Results in the same laboratory should not be considered suspect unlessthey differ by more than the amounts shown in Table 2. On the basis of test errorResults differing by less than “r alone, thedifference between two results obtained in the same labora
46、tory on the same material will be expected to exceed this value only5 % of the time.” have a 95 % probability of being correct.14.1.2 ReproducibilityResults submitted by each of two laboratories should not be considered suspect unless they differ bymore than the amount shown in Table 2. On the basis
47、 of test errorResults differing by less than “R alone, the difference betweentwo test results obtained in different laboratories on the same material will be expected to exceed this value only 5 % of the time.”have a 95 % probability of being correct.14.2 BiasSince there is no accepted reference mat
48、erial suitable for determining the bias for the procedure in this test methodfor measuring specific impurities, bias has not been determined.15. Quality Guidelines15.1 Laboratories shall have a quality control system in place.15.2 Confirm the performance of the test instrument or test method by anal
49、yzing a quality control sample following theguidelines of standard statistical quality control practices.15.3 A quality control sample is a stable material isolated from the production process and representative of the sample beinganalyzed.15.4 When QA/QC protocols are already established in the testing facility, these protocols are acceptable when they confirmthe validity of test results.15.5 When there are no QA/QC protocols established in the testing facility, use the guidelines described in Guide D6809 orsimilar statistical quality cont
