1、Designation: D7057 13Standard Test Method forAnalysis of Isopropylbenzene (Cumene) by GasChromatography (External Standard)1This standard is issued under the fixed designation D7057; 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*1.1 This test method covers the determination of the purityof isopropylbenzene (cumene) by gas chromatography
3、. 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-prop
4、ylbenzene, 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 Tab
5、le 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 E29.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are
6、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 to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations pri
7、or to use. For specific hazardstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D3437 Practice for Sampling and Handling Liquid CyclicProductsD4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsD4790 Terminology of Aromatic Hydrocarbons and RelatedChemica
8、lsD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons 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 Conductin
9、g 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, 29CFR paragraphs 1910.1000 and1910.120033. Terminology3.1 See Terminology D4790 for definition of te
10、rms used inthis test method.4. Summary of Test Method4.1 Cumene (isopropylbenzene) is analyzed by a gas chro-matograph (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 impuritie
11、s are measured and converted to concen-trations via an external standard methodology. Purity by GC(the Cumene content) is 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)
12、 thermal decomposition in theinlet of the GC. Results are reported in weight percent.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.07 on Styrene, Ethylbenzene and C9 and C10 Aromatic
13、Hydrocarbons.Current edition approved June 1, 2013. Published June 2013. Originallyapproved in 2004. Last previous edition approved in 2009 as D7057 09. DOI:10.1520/D7057-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
14、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 20401, http:/www.access.gpo.gov.*A Summary of Changes se
15、ction appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 This test method is suitable for setting specifications onthe materials referenced in 1.2 and for use as an internal q
16、ualitycontrol tool where isopropylbenzene is produced or is used ina manufacturing process. It may also be used in developmentor research work involving isopropylbenzene.5.2 This test method is useful in determining the purity ofisopropylbenzene with normal impurities present. If extremelyhigh boili
17、ng or unusual impurities are present in theisopropylbenzene, this test method would not necessarilydetect them and 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 c
18、hromatogram thereby givingincorrect results unless 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 hydrocar
19、bons commonly present fromthe isopropylbenzene manufacturing 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.
20、 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 significant impuriti
21、es from isopropylbenzene. Thecolumn described in Table 2 has been used successfully andshall be used as a referee in cases of dispute. Unless the analystcan be sure of peak identity, for example by gaschromatography-mass spectrometry (GC-MS), the use of thecolumn in Table 2 is strongly recommended.6
22、.3 RecorderElectronic integration is required.6.4 InjectorThe specimen must be precisely and repeat-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 b
23、e reliably 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 of the Commit-tee on Analytical Reagents of the American Chemical So
24、ciety,where such specifications are available.4Other 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.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical
25、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., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville
26、,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+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
27、+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 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 5240
28、o-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-diisopropylbenzene(13DIPB) 0.727+0.010*13DIPB 1.570+0.720*13DIPB 12101,4-diisopropylbenzene(14DIPB) 0.435+0.013*14DIPB 1.112+0.0
29、40*14DIPB 1285NonAromatics(NA) 0.441+0.242*NA 1.663+0.306*NA 595TABLE 2 Recommended Operating ConditionsDetector flame ionizationInjection Port capillary splitterColumn A:Tubing fused silicaStationary Phase crosslinkedpolydimethylsilicone (HP-1,DB-1 or equiv)Film Thickness, m 1.0Length, m 60Diameter
30、, 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 to250C, hold for 7.5 minCarrier Gas HeliumFlow Rate, mls/min 3Split Ratio 60:1Sample Size, L 1.0D7057 1327.2 Carrier Gas, Makeup, and Detector GasesHelium,hydrogen, ni
31、trogen, 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, and hydrocarbons.7.3 Compressed AirPurify air to remove water and hydro-carbons. Air fo
32、r a FID should contain less than 0.1 ppm THC.7.4 Pure Compounds for CalibrationThe purity of allreagents should be 99.9 % or greater. If the purity is less than99 % the concentration and identification of impurities must beknown so that the composition of the standard can be adjustedfor the presence
33、 of the impurities.8. Hazards8.1 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 manufac
34、turers instructions for mounting andconditioning the column into the chromatograph and adjustingthe instrument to the conditions described in Table 2 allowingsufficient time for the equipment to reach equilibrium. SeePractice E355 for additional information on gas chromatogra-phy practices and termi
35、nology.11. Calibration11.1 Prepare a synthetic mixture of high purity cumenecontaining impurities at concentrations representative of thoseexpected in the samples to be analyzed in accordance withPractice D4307. The weight of each hydrocarbon impuritymust be measured to the nearest 0.1 mg. Because t
36、he avail-ability of stock cumene with a purity higher than 99.97 % isFIG. 1 Typical Chromatogram using Conditions in Table 2D7057 133problematic, the method of standard additions may be requiredfor impurities such as tert-butylbenzene and n-propylbenzene,as well as for a number of the other impuriti
37、es 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 illustrated in Fig. 1 based on the conditions listedin Table 2.11.3 Determine the response factor for each impurity in thecalibra
38、tion 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.11.4 Initially analyze the calibration solution a minimum ofthree times and calculate an average Rfi. Subsequent calibra-tions
39、 may be a single analysis as long as the response factorsfor all components of interest are within 65 % of the 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 and
40、non-aromatics quantification.12. Procedure12.1 Inject into the gas chromatograph an appropriateamount of sample sufficient to satisfy the sensitivity conditionsas detailed in 6.1 and start the analysis.12.2 Obtain a chromatogram and peak integration report.Fig. 1 illustrates a typical analysis of cu
41、mene using the columnand conditions outlined in Table 2.13. Calculations13.1 Calculate the concentration of each impurity as fol-lows:Ci 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 conc
42、entration of all impurities inwt % (excluding AP and DMBA as per 5.3) as follows:Ct5(Ci/10000 (3)where:Ct= total concentration of all impurities.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 near
43、est 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 be used to judge theacceptability at the 95 % probability level of the resultsobtained by this test method. The criteria were derived from anInterlaboratory study o
44、f five samples analyzed in triplicate byfive laboratories. Practice E691 was followed for the designand analysis of the data; the details are given in ASTMResearch Report RR:D16-1033.15.2 RepeatabilityResults in the same laboratory shouldnot be considered suspect unless they differ by more than thea
45、mounts calculated from the appropriate equations in Table 1.Results differing by less than “r” have a 95 % probability ofbeing correct.15.3 ReproducibilityResults submitted by two laborato-ries should not be considered suspect unless they differ bymore than the amounts calculated from the appropriat
46、e equa-tions in Table 1. Results differing by less than “R”havea95%probability of being correct.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
47、Guidelines16.1 Laboratories shall have a quality control system 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 mate
48、rial isolatedfrom the production process and representative 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
49、testing facility, use the guidelines described in GuideD6809 or similar statistical quality control practices.17. Keywords17.1 alpha-methylstyrene; analysis by gas chromatography;benzene; butylbenzene; cumene; cymene; diisopropylbenzene;ethylbenzene; isopropylbenzene; methyl cumene; nonaromatichydrocarbons; propylbenzene; toluene5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D16-1033.D7057 134SUMMARY OF CHANGESCommittee D16 has identified the location of selected chan
