1、Designation: D 7057 04Standard Test Method forAnalysis of Isopropylbenzene (Cumene) by GasChromatography (External Standard)1This standard is issued under the fixed designation D 7057; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the purityof isopropylbenzene (cumene) by gas chromatograp
3、hy. Cali-bration of the gas chromatography system is done by theexternal standard calibration technique.1.2 This test method has been found applicable to themeasurement of impurities such as nonaromatic hydrocarbons,benzene, toluene, ethylbenzene, phenol, cymenes,t-butylbenzene, n-butylbenzene, n-pr
4、opylbenzene, alpha-methylstyrene, sec-butylbenzene, and diisopropylbenzenes,which are impurities that can be found in isopropylbenzene.The latter impurities can be analyzed over a range of 1 mg/kgto 500 mg/kg by this method (see Table 1). The limit ofdetection for these impurities is summarized in T
5、able 1 as well.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 method ofPractice E 29.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with
6、 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 specific hazardstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D 3437 Practice for Sa
7、mpling and Handling Liquid CyclicProductsD 4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsD 4790 Terminology of Aromatic Hydrocarbons and Re-lated ChemicalsD 6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE
8、 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE 355 Practice for Gas Chromatography Terms and Rela-tionshipsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1510 Practice for Installing Fused Silica
9、 Open TubularColumns in Gas Chromatographs2.2 Other Document:OSHA Regulations, 29CFR paragraphs 1910.1000 and1910.120033. Terminology3.1 See Terminology D 4790 for definition of terms used inthis test method.4. Summary of Test Method4.1 Cumene (isopropylbenzene) is analyzed by a gas chro-matograph (
10、GC) equipped with a flame ionization detector(FID). A precisely repeatable volume of the sample to beanalyzed is injected onto the gas chromatograph. The peakareas of the impurities are measured and converted to concen-trations via an external standard methodology. Purity by GC(the Cumene content) i
11、s calculated by subtracting the sum ofthe impurities from 100.00, excluding Acetophenone (AP) and2-phenyl-2-propanol (DMPC or DMBA) which are artifacts ofcumene hydroperoxide (CHP) thermal decomposition in theinlet of the GC. Results are reported in weight percent.5. Significance and Use5.1 This tes
12、t method is suitable 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.1This test method is
13、 under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.07 on Styrene, Ethylbenzene, and C9and C10AromaticHydrocarbons.Current edition approved June 1, 2004. Published July 2004.2For referenced ASTM standards, vi
14、sit 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 Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 204
15、02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 This test method is useful in determining the purity ofisopropylbenzene with normal impurities present. If extremelyhigh boiling or unusual impurities are present in the isopropy
16、-lbenzene, this test method would not necessarily detect themand the purity calculation would be erroneous.5.3 Cumene hydroperoxide, if present, will yield thermaldecomposition products, primarily AP and DMPC as stated in4.1, that will elute in the chromatogram thereby givingincorrect results unless
17、 they are excluded as indicated in 4.1. Itis also possible to get erroneous results for trace alpha-methylstyrene present in isopropylbenzene if the inlet hasbecome unduly contaminated with non-volatile foreign sub-stances.5.4 The nonaromatic hydrocarbons commonly present fromthe isopropylbenzene ma
18、nufacturing process, particularly anon-zeolitic one, will interfere with the determination ofxylenes (if present).6. Apparatus6.1 Gas ChromatographAny instrument having a flameionization detector that can be operated at the conditions givenin Table 2. The system should have sufficient sensitivity to
19、obtain 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 significant impurities from isopropylbenzene. Thecolumn described in
20、Table 2 has been used successfully. Unlessthe analyst can be sure of peak identity, for example by gaschromatography-mass spectrometry (GC-MS), the use of thecolumn in Table 2 is strongly recommended.6.3 RecorderElectronic integration is required.6.4 InjectorThe specimen must be precisely and repeat
21、-edly injected into the gas chromatograph. An automatic sampleinjection device is highly recommended. Manual injection canbe employed if the precision stated in Table 1, Summary ofPrecision Data, can be reliably and consistently satisfied.7. Reagents and Materials7.1 Purity of ReagentsReagent grade
22、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 ascert
23、ained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 GasesHelium, Hydrogen, Nitrogen, or other as Car-rier. Carrier, makeup, and detector gases 99.999 % minimumpurity. Oxygen in carrier gas less than 1 ppm, less than 0.5 ppmis
24、preferred. Purify carrier, makeup, and detector gases toremove oxygen, water, and hydrocarbons. Purify air to removehydrocarbons and water, and the air used should be zero gradeor better.8. Hazards8.1 Consult current OSHA regulations, suppliers MaterialSafety Data Sheets, and local regulations for a
25、ll materials listedin this test method.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,
26、 U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Summary of Precision Data (mg/kg)Compound Repeatability ReproducibilityRangeStudiedBenzene 1.004+0.006*Benzene 0.924+0.158*Benzene 1.0295Toluene 0.644+0.009*Toluene 1.505
27、+0.069*Toluene 0.2260Ethylbenzene (EB) 1.249+0.022*EB 2.534+0.230*EB 5370n-Propylbenzene (NPB) -0.369+0.015*NPB -6.793+0.214*NPB 180465Phenol (PHE) 1.926+.0095*PHE 3.718+0.207*PHE 1225alpha-methylstyrene(AMS) 1.368+0.057*AMS 21.181+0.976*AMS 6305tert-Butylbenzene(TBB) 1.666+0.011*TBB 4.126+0.086*TBB
28、 2250sec-Butylbenzene(SBB) 0.635+0.010*SBB 0.891+0.090*SBB 2245m-Cymene 0.618+0.011*m-Cymene 1.811+0.181*m-Cymene 5240o-Cymene 0.498+0.012*o-Cymene 1.951+0.156*o-Cymene 1160p-Cymene 0.485+0.019*p-Cymene 1.618+0.097*p-Cymene 2270n-Butylbenzene(NBB) 0.445+0.030*NBB 2.600+0.045*NBB 0.32651,3-diisopropy
29、lbenzene(13DIPB) 0.727+0.010*13DIPB 1.570+0.720*13DIPB 12101,4-diisopropylbenzene(14DIPB) 0.435+0.013*14DIPB 1.112+0.040*14DIPB 1285NonAromatics(NA) 0.441+0.242*NA 1.663+0.306*NA 595TABLE 2 Instrumental ParametersDetector flame ionizationInjection Port capillary splitterColumn A:Tubing fused silicaS
30、tationary Phase crosslinked polydimethylsilicone (HP-1, DB-1 or equiv)Film Thickness, m 1.0Length, m 60Diameter, mm 0.32Temperatures:Injector, C 250Detector, C 300Oven, C 85 hold for 13 minRamp 1 = 6C/min to 125C, hold for 2 minRamp 2 = 30C/min to 250C, hold for 7.5 minCarrier Gas HeliumFlow Rate, m
31、ls/min 3Split Ratio 60:1Sample Size, L 1.0D70570429. Sampling and Handling9.1 Sample the material in accordance with PracticeD 3437.10. Preparation of Apparatus10.1 Follow manufacturers instructions for mounting andconditioning the column into the chromatograph and adjustingthe instrument to the con
32、ditions described in Table 2 allowingsufficient time for the equipment to reach equilibrium. SeePractices E 1510 and E 355 for additional information on gaschromatography practices and terminology.11. Calibration11.1 Prepare a synthetic mixture of high purity cumenecontaining impurities at concentra
33、tions representative of thoseexpected in the samples to be analyzed in accordance withPractice D 4307. The weight of each hydrocarbon impuritymust be measured to the nearest 0.1 mg. Because the avail-ability of stock cumene with a purity higher than 99.97 % isproblematic, the method of standard addi
34、tions may be requiredfor impurities such as tert-butylbenzene and n-propylbenzene,as well as for a number of the other impurities listed in 1.2 thatare commonly present.11.2 Inject the resulting solution from 11.1 into the gaschromatograph, collect and process the data. A typical chro-matogram is il
35、lustrated in Fig. 1 based on the conditions listedin Table 2.11.3 Determine the response factor for each impurity in thecalibration mixture as follows:Rfi 5 Ci/Ai (1)where:Rfi = response factor for impurity i,Ci = concentration of impurity i in the calibration mixture,andAi = peak area of impurity i
36、.FIG. 1 Typical Chromatogram using Conditions in Table 2D705704311.4 Initially analyze the calibration solution a minimum ofthree times and calculate an average Rfi. Subsequent calibra-tions may be a single analysis as long as the response factorsfor all components of interest are within 65 % of the
37、 initialvalidation response factors. A “rolling” average as defined bymost modern chromatographic software may also be used. Theresponse factor for tert-butylbenzene is used for unknowns andnon-aromatics quantification.12. Procedure12.1 Inject into the gas chromatograph an appropriateamount of sampl
38、e as previously determined according to 6.1and start the analysis.12.2 Obtain a chromatogram and peak integration report.Fig. 1 illustrates a typical analysis of cumene using the columnand conditions outlined in Table 2.13. Calculations13.1 Calculate the concentration of each impurity as fol-lows:Ci
39、 5 Ai! Rfi! (2)where:Ci = concentration of component i in mg/kg,Ai = peak area of component i, andRfi = response factor for component i,13.2 Calculate the total concentration of all impurities inwt % (excluding AP and DMBA as per 5.3) as follows:Ct5(Ci/10000 (3)where:Ct= total concentration of all i
40、mpurities.13.3 Calculate the purity of isopropylbenzene as follows:Cumene, weight percent 5 100.00 2 Ct(4)14. Report14.1 Report the individual impurities to the nearest mg/kg.14.2 Report the purity of isopropylbenzene to the nearest0.01 wt %.15. Precision and Bias515.1 The criteria in Table 1 should
41、 be used to judge theacceptability at the 95 % probability level of the resultsobtained by this test method. The criteria were derived from anInterlaboratory study of five samples analyzed in triplicate byfive laboratories. The results were derived using the protocolset forth in Practice E 691.15.2
42、RepeatabilityResults in the same laboratory shouldnot be considered suspect unless they differ by more than theamounts calculated from the appropriate equations in Table 1.15.3 ReproducibilityResults submitted by two laborato-ries should not be considered suspect unless they differ bymore than the a
43、mounts calculated from the appropriate equa-tions in Table 1.15.4 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod for measuring isopropylbenzene purity, bias has notbeen determined.16. Quality Guidelines16.1 Refer to standard Gu
44、ide D 6809 for suggested QA/QCactivities that can be used as a part of this method. It isrecommended that the operator of this method select andperform relevant QA/QC activities like the ones in GuideD 6809 to help ensure the quality of data generated by thismethod.17. Keywords17.1 alpha-methylstyre
45、ne; analysis by gas chromatography;benzene; butylbenzene; cumene; cymene; diisopropylbenzene;ethylbenzene; isopropylbenzene; methyl cumene; nonaromatichydrocarbons; propylbenzene; tolueneASTM International takes no position respecting the validity of any patent rights asserted in connection with any
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49、rive, 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), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).5Supporting data are available from ASTM International Headquarters. RequestRR:D161033.D7057044
