1、Designation: D3760 12Standard Test Method forAnalysis of Isopropylbenzene (Cumene) by GasChromatography1This standard is issued under the fixed designation D3760; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. 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 the purityof isopropylbenzene (cumene) by gas chromatography.1.2 This test metho
3、d has been found applicable to themeasurement of impurities such as nonaromatic hydrocarbons,benzene, ethylbenzene, t-butylbenzene, n-propylbenzene,alpha-methylstyrene, sec-butylbenzene, anddiisopropylbenzene, which are common to the manufacturingprocess of isopropylbenzene. Limit of detection for t
4、heseimpurities is 10 mg/kg (see 5.1). This method has been foundapplicable for concentrations of various components up to 571ppm.1.3 In determining the conformance of the test results usingthis method to applicable specifications, results shall berounded off in accordance with the rounding-off metho
5、d 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 with its use. It is theresponsibility of the user of this standard
6、to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Section 7.2. Referenced Documents2.1 ASTM Standards:2D3437 Practice for Sampling and Handling Liquid CyclicProductsD6809 Guide for Quality
7、 Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and Relation-shipsE6
8、91 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1510 Practice for Installing Fused Silica Open TubularCapillary Columns in Gas Chromatographs2.2 Other Document:OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120033. Summary of Test Method3.1 A kno
9、wn amount of internal standard is added to asample of isopropylbenzene. The prepared sample is mixedand analyzed by a gas chromatograph equipped with a flameionization detector (FID). The peak area of each impurity andthe internal standard is measured and the amount of eachimpurity is calculated fro
10、m the ratio of the peak area of theinternal standard versus the peak area of the impurity. Purity byGC (the isopropylbenzene content) is calculated by subtractingthe sum of the impurities found from 100.00. Results arereported in weight percent.4. Significance and Use4.1 This test method is suitable
11、 for setting specifications onthe materials referenced in 1.2 and for use as an internal qualitycontrol tool where isopropylbenzene is produced or is used ina manufacturing process. It may also be used in developmentor research work involving isopropylbenzene.4.2 This test method is useful in determ
12、ining the purity ofisopropylbenzene with normal impurities present includingdiisopropylbenzenes. If extremely high boiling or unusual1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.07
13、on Styrene, Ethylbenzene and C9 and C10 AromaticHydrocarbons.Current edition approved Dec. 15, 2012. Published January 2013. Originallyapproved in 1979. Last previous edition approved in 2008 as D3760 08. DOI:10.1520/D3760-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orco
14、ntact 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. Capitol St., NW, Mail Stop: SDE, Washington, DC 2040
15、1, http:/www.access.gpo.gov.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1impurities are present in the isopropylbenzene, this test methodwould not necessarily detect
16、them and the purity calculationwould be erroneous.4.3 Cumene hydroperoxide, if present, will yield decompo-sition products that will elute in the chromatogram therebygiving incorrect results.4.4 The nonaromatic hydrocarbons commonly present fromthe isopropylbenzene manufacturing process will interfe
17、re withthe determination of benzene when Column A in Table 1 isused.4.5 The internal standard must be sufficiently resolved fromany impurity and the isopropylbenzene peak.5. Apparatus5.1 Gas ChromatographAny instrument having a flameionization detector that can be operated at the conditions givenin
18、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 backgroundnoise.5.2 ColumnsThe choice of column is based on resolutionrequirements. Any column may be used that is capable ofresolving all signi
19、ficant impurities from isopropylbenzene andfrom the internal standard. The columns and conditions de-scribed in Table 1 have been used successfully and shall beused as referee in cases of dispute.5.3 RecorderElectronic integration is recommended.6. Reagents and Materials6.1 Purity of ReagentsReagent
20、 grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first
21、 ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.1.1 Internal StandardNormal Butylbenzene (nBB) isthe recommended internal standard of choice. Other com-pounds may be found acceptable provided they meet thecriteria as
22、defined in 4.5 and 6.1.6.2 Carrier Gas, Makeup, and Detector GasesHelium,hydrogen, nitrogen, or other carrier, makeup and detector gases99.999 % minimum purity. Oxygen in carrier gas less than 1ppm, less than 0.5 ppm is preferred. Purify carrier, makeup,and detector gases to remove oxygen, water, an
23、d hydrocarbons.6.3 Compressed AirPurify air to remove water and hydro-carbons. Air for an FID should contain less than 0.1 ppm THC.6.4 Pure Compounds for CalibrationThe purity of allreagents should be 99.9 % or greater. If the purity is less than99 %, the concentration and identification of impuriti
24、es mustbe known so that the composition of the standard can beadjusted for the presence of the impurities.7. Hazards7.1 Consult current OSHA regulations and suppliers Mate-rial Safety Data Sheets on handling materials listed in this testmethod.8. Sampling and Handling8.1 Sample the material in accor
25、dance with Practice D3437.9. Preparation of Apparatus9.1 Follow manufacturers instructions for mounting andconditioning the column into the chromatograph and adjustingthe instrument to the conditions described in Table 1 allowingsufficient time for the equipment to reach equilibrium. SeePractice E15
26、10 for more information on column installation.See Practice E355 for additional information on gas chroma-tography practices and terminology.10. Procedure10.1 Into a 100-mL volumetric flask, add 100 L of nBB to99.90 mL of cumene. Mix well. Assuming a density of 0.856for nBB and 0.857 for cumene, the
27、 resulting nBB concentrationwill be 0.1000 weight %.10.2 Inject into the gas chromatography an appropriateamount of sample as previously determined according to 6.1and start the analysis.10.3 Obtain a chromatograph and peak integration report.Fig. 1 and Fig. 2 illustrate a typical analysis of cumene
28、 forColumns A and B, respectively.4Reagent 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 for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K.
29、, and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Recommended Operating ConditionsColumn A Column BDetector Flame Ionization Flame IonizationColumn:Tubing fused silica fused silicaStationary phase polyethylene glycol methyl s
30、iliconeSolid support crosslinked crosslinkedFilm thickness 0.25 0.5 Length, m 50 50Diameter, mm 0.32 mm ID 0.32 mm IDTemperatures:Injector, C 275 275Detector, C 300 300Oven:Initial, C 60 35Time 1, min 10 10Final, C 175 275Rate, C/min 10 5Time 2, min 10 0Carrier gas hydrogen heliumFlow rate, mL/min 1
31、.0 1.0Split ratio 100:1 100:1Sample size, L 1.0 1.0D3760 12211. Calculations11.1 Determine the area defined by each peak in thechromatogram.11.2 Calculate the percent concentration of the total nonaro-matics and each impurity as follows:Ci5Ai!C2!A2!(1)where:Ci= concentration of component i, weight %
32、,Ai= peak area of component i,A2= peak area of nBB,C2= concentration of nBB, weight %.11.3 Calculate the total concentration of all impurities asfollows:Ct5(Ci(2)where:Ct= total concentration of all impurities.11.4 Calculate the purity of isopropylbenzene as follows:isopropylbenzene, weight % 5 100.
33、000 2 Ct(3)12. Report12.1 Report the individual impurities to the nearest0.0001 %.12.2 Report the purity of isopropylbenzene to the nearest0.001 weight%.13. Precision and Bias513.1 PrecisionThe following criteria should be used tojudge the acceptability of results obtained by this test method(95 % c
34、onfidence level). The precision criteria were derivedfrom an ILS that was conducted using the conditions listedunder Column B in Table 1 which included nine laboratoriesanalyzing four samples in triplicate. Practice E691 was fol-lowed for the design and analysis of the data; the details aregiven in
35、ASTM Research Report RR:D16-1032.13.1.1 Intermediate Precision (formerly calledRepeatability)Results should not be suspect unless theydiffer by more than the amount listed in Table 2 and Table 3.Results differing by less than “r” have a 95 % probability ofbeing correct.5Supporting data have been fil
36、ed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D16-1032.FIG. 1 Typical Chromatogram using Conditions for Column AD3760 123FIG. 2 Typical Chromatogram using Conditions for Column BD3760 12413.1.2 ReproducibilityResults submitted by two labsshould not be cons
37、idered suspect unless they differ by morethan that shown in Table 2 and Table 3. Results differing byless than “R” have a 95 % probability of being correct.TABLE 2 Typical Values for Repeatability (r) and Reproducibility(R) for Selected Cumene Components Using the Conditions inColumn B of Table 1Com
38、ponentConcentration,wt %Repeatability Reproducibilitya-Methylstyrene 0.0065 0.0003 0.00060.0083 0.0007 0.00100.0104 0.0012 0.0014Benzene 0.0024 0.00023 0.00088Ethylbenzene 0.0042 0.0004 0.00300.0080 0.0008 0.00380.0099 0.0009 0.0042Nonaromatics 0.0163 0.0009 0.00480.0571 0.0050 0.0063n-Propylbenzene
39、 0.0192 0.0018 0.00170.0218 0.0010 0.00130.0246 0.0001 0.0009s-Butylbenzene 0.0024 0.0002 0.00220.0037 0.0002 0.00310.0059 0.0004 0.0044t-Butylbenzene 0.0067 0.0003 0.00090.0106 0.0004 0.00130.0283 0.0010 0.0035Cumene 99.8443 0.0046 0.088899.8657 0.0062 0.075299.9221 0.0106 0.039299.9386 0.0119 0.02
40、87TABLE 3 Intermediate Precision (formerly called Repeatability)and ReproducibilityCumeneRepeatability = 0.07801() 7.7843Reproducibility = 0.63789() + 63.7785t-ButylbenzeneRepeatability = 0.031894() + 0.00009Reproducibility = 0.120596() + 0.0000648s-ButylbenzeneRepeatability = 0.054069() + 0.0000437
41、Reproducibility = 9.60703() + 0.000817n-PropylbenzeneRepeatability = 0.30407 () + 0.007613Reproducibility = 0.14927() + 0.004605a-MethylstyreneRepeatability = 0.21785() 0.0010752Reproducibility = 0.20833() 0.000761BenzeneRepeatability = 0.095( )Reproducibility = 0.367175()NonaromaticsRepeatability =
42、 0.098932() 0.000697Reproducibility = 0.03733() + 0.004214EthylbenzeneRepeatability = 0.099441() 0.000045Reproducibility = 0.208332() + 0.0021557D3760 12513.2 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod for measuring isoprop
43、ylbenzene purity, bias has notbeen determined.14. Quality Guidelines14.1 Laboratories shall have a quality control system inplace.14.1.1 Confirm the performance of the test instrument ortest method by analyzing a quality control sample followingthe guidelines of standard statistical quality control
44、practices.14.1.2 A quality control sample is a stable material isolatedfrom the production process and representative of the samplebeing analyzed.14.1.3 When QA/QC protocols are already established inthe testing facility, these protocols are acceptable when theyconfirm the validity of test results.1
45、4.1.4 When there are no QA/QC protocols established inthe testing facility, use the guidelines described in GuideD6809 or similar statistical quality control practices.15. Keywords15.1 alpha methylstyrene; analysis by gas chromatography;benzene; butylbenzene; cumene; ethylbenzene; isopropylben-zene;
46、 nonaromatic hydrocarbons; propylbenzeneSUMMARY OF CHANGESCommittee D16 has identified the location of selected changes to this standard since the last issue (D3760 - 08)that may impact the use of this standard. (Approved December 15, 2012.)(1) Section 1 Updated to current Editorial Guidelines.(2) S
47、ection 6 Updated to current Editorial Guidelines.(3) Section 9 Updated to current Editorial Guidelines.(4) Section 13 Updated to current Editorial Guidelines.(5) Section 14 Updated to current Editorial Guidelines.(6) Table 1 and Table 2 Headers updated to current EditorialGuidelines.ASTM Internation
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