1、Designation: D7057 13D7057 18Standard 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 re
2、vision, 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 purity of isopropylbenzene (cumene) by gas chrom
3、atography. Calibrationof the gas chromatography system is done by the external standard calibration technique.1.2 This test method has been found applicable to the measurement of impurities such as nonaromatic hydrocarbons, benzene,toluene, ethylbenzene, phenol, cymenes, t-butylbenzene, n-butylbenze
4、ne, n-propylbenzene, alpha-methylstyrene, sec-butylbenzene, and diisopropylbenzenes, which are impurities that can be found in isopropylbenzene. The latter impurities can beanalyzed over a range of 1 mg/kg to 500 mg/kg by this method (see Table 1). The limit of quantitation averages 3.8 mg/kg whilet
5、he limit of detection for these impurities is summarized in averages 1.1 mg/kg.Table 1 as well.1.3 In determining the conformance of the test results using this method to applicable specifications, results shall be roundedoff in accordance with the rounding-off method of Practice E29.1.4 The values
6、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 any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safe
7、ty safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use. For specific hazard statements, see Section 8.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablish
8、ed in the Decision on Principles for the Development of International Standards, 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 ProductsD430
9、7 Practice for Preparation of Liquid Blends for Use as Analytical StandardsD4790 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 in Test
10、 Data to Determine Conformance with SpecificationsE355 Practice for Gas Chromatography Terms and RelationshipsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatograp
11、hs2.2 Other Document:OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.120033. Terminology3.1 See Terminology D4790 for definition of terms used in this test method.1 This test method is under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons Aromatic, Industrial, Specialty and Re
12、lated Chemicals and is the directresponsibility of Subcommittee D16.07 on Styrene, Ethylbenzene and C9 and C10 Aromatic Hydrocarbons.Current edition approved June 1, 2013Jan. 1, 2018. Published June 2013January 2018. Originally approved in 2004. Last previous edition approved in 20092013 as D7057 09
13、.13. DOI: 10.1520/D7057-13.10.1520/D7057-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standardsstandards Document Summary page on the ASTM website.3 Availa
14、ble 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.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
15、 to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends 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 Su
16、mmary 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 States14. Summary of Test Method4.1 Cumene (isopropylbenzene) is analyzed by a gas chromatograph (GC) equipped with a flame ionizatio
17、n detector (FID). Aprecisely repeatable volume of the sample to be analyzed is injected onto the gas chromatograph. The peak areas of the impuritiesare measured and converted to concentrations via an external standard methodology. Purity by GC (the Cumene content) iscalculated by subtracting the sum
18、 of the impurities from 100.00, excluding Acetophenone (AP) and 2-phenyl-2-propanol (DMPCor DMBA) which are artifacts of cumene hydroperoxide (CHP) thermal decomposition in the inlet of the GC. Results are reportedin weight percent.5. Significance and Use5.1 This test method is suitable for setting
19、specifications on the materials referenced in 1.2 and for use as an internal qualitycontrol tool where isopropylbenzene is produced or is used in a manufacturing process. It may also be used in development orresearch work involving isopropylbenzene.5.2 This test method is useful in determining the p
20、urity of isopropylbenzene with normal impurities present. If extremely highboiling or unusual impurities are present in the isopropylbenzene, this test method would not necessarily detect them and the puritycalculation would be erroneous.5.3 Cumene hydroperoxide, if present, will yield thermal decom
21、position products, primarilyAPand DMPC as stated in 4.1, thatwill elute in the chromatogram thereby giving incorrect results unless they are excluded as indicated in 4.1. It is also possible toget erroneous results for trace alpha-methylstyrene present in isopropylbenzene if the inlet has become und
22、uly contaminated withnon-volatile foreign substances.5.4 The nonaromatic hydrocarbons commonly present from the isopropylbenzene manufacturing process, particularly anon-zeolitic one, will interfere with the determination of xylenes (if present).6. Apparatus6.1 Gas ChromatographAny instrument having
23、 a flame ionization detector that can be operated at the conditions given inTable 2. The system should have sufficient 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 req
24、uirements.Any column may be used that is capable of resolvingall significant impurities from isopropylbenzene. The column described in Table 2 has been used successfully and shall be usedas a referee in cases of dispute. Unless the analyst can be sure of peak identity, for example by gas chromatogra
25、phy-massspectrometry (GC-MS), the use of the column in Table 2 is strongly recommended.6.3 RecorderElectronic integration is required.Chromatographic data systems are preferred but electronic integration may beused if the user can demonstrate that the results are consistent with the precision statem
26、ent. Recorders are not considered adequatefor meeting the precision requirements of this standard.6.4 InjectorThe specimen must be precisely and repeatedly injected into the gas chromatograph. An automatic sampleinjection device is highly recommended. Manual injection can be employed if the precisio
27、n stated in Table 1, Summary ofPrecision Data, can be reliably and consistently satisfied.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committe
28、e on Analytical Reagents of the American Chemical Society, whereTABLE 1 Summary of Precision Data (mg/kg)Compound Repeatability Reproducibility RangeStudiedBenzene 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 2.5
29、34+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 2250sec-Butylbenzene(SBB) 0.635+0.010*SBB 0.891+0.090*SB
30、B 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-diisopropylbenzene(13DIPB) 0.727+0.010*13DIPB 1.570+0.720*13DIPB 12
31、101,4-diisopropylbenzene(14DIPB) 0.435+0.013*14DIPB 1.112+0.040*14DIPB 1285NonAromatics(NA) 0.441+0.242*NA 1.663+0.306*NA 595D7057 182such specifications are available.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use withou
32、t lessening the accuracy of the determination.7.2 Carrier Gas, Makeup, and Detector GasesHelium, hydrogen, nitrogen, or other carrier, makeup and detector gases99.999 % minimum purity. Oxygen in carrier gas less than 1 ppm, less than 0.5 ppm is preferred. Purify carrier, makeup, anddetector gases to
33、 remove oxygen, water, and hydrocarbons.7.3 Compressed AirPurify air to remove water and hydrocarbons. Air for a FID should contain less than 0.1 ppm THC.7.4 Pure Compounds for CalibrationThe purity of all reagents should be 99.9 % or greater. If the purity is less than 99 %the concentration and ide
34、ntification of impurities must be known so that the composition of the standard can be adjusted for thepresence of the impurities.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 H
35、andling9.1 Sample the material in accordance with Practice D3437.10. Preparation of Apparatus10.1 Follow manufacturers instructions for mounting and conditioning the column into the chromatograph and adjusting theinstrument to the conditions described in Table 2 allowing sufficient time for the equi
36、pment to reach equilibrium. See Practice E355for additional information on gas chromatography practices and terminology.11. Calibration11.1 Prepare a synthetic mixture of high purity cumene containing impurities at concentrations representative of those expectedin the samples to be analyzed in accor
37、dance with Practice D4307. The weight of each hydrocarbon impurity must be measuredto the nearest 0.1 mg. Because the availability of stock cumene with a purity higher than 99.97 % is problematic, the method ofstandard additions may be required for impurities such as tert-butylbenzene and n-propylbe
38、nzene, as well as for a number of theother impurities listed in 1.2 that are commonly present.11.2 Inject the resulting solution from 11.1 into the gas chromatograph, collect and process the data. A typical chromatogramis illustrated in Fig. 1 based on the conditions listed in Table 2.11.3 Determine
39、 the response factor for each impurity in the calibration mixture as follows:Rfi5Ci/Ai (1)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 Standa
40、rds 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 Recommended Operating ConditionsDetector flame ionizationInjection Port capillary splitterColumn A:Tubing fused sil
41、icaStationary Phase crosslinkedpolydimethylsilicone (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 to250C, hold for 7.5 minCarrier Gas HeliumFlow Rate, m
42、ls/min 3Split Ratio 60:1Sample Size, L 1.0D7057 183where: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 of three times and calculate an average Rfi. Subsequent
43、 calibrationsmay be a single analysis as long as the response factors for all components of interest are within 65 % of the initial validationresponse factors. A “rolling” average as defined by most modern chromatographic software may also be used. The response factorfor tert-butylbenzene is used fo
44、r unknowns and non-aromatics quantification.12. Procedure12.1 Inject into the gas chromatograph an appropriate amount of sample sufficient to satisfy the sensitivity conditions as detailedin 6.1 and start the analysis.12.2 Obtain a chromatogram and peak integration report. Fig. 1 illustrates a typic
45、al analysis of cumene using the column andconditions outlined in Table 2.13. Calculations13.1 Calculate the concentration of each impurity as follows:Ci5Ai! Rfi! (2)FIG. 1 Typical Chromatogram using Conditions in Table 2D7057 184where:Ci = concentration of component i in mg/kg,Ai = peak area of comp
46、onent i, andRfi = response factor for component i,13.2 Calculate the total concentration of all impurities in wt % (excluding AP and DMBA as per 5.3) as follows:Ct 5(Ci/10000 (3)where:Ct = total concentration of all impurities.13.3 Calculate the purity of isopropylbenzene as follows:Cumene,weight pe
47、rcent5100.002Ct (4)14. Report14.1 Report the individual impurities to the nearest mg/kg.14.2 Report results less than the LOD as 1 mg/kg.14.3 Report the purity of isopropylbenzene to the nearest 0.01 wt %.15. Precision and Bias515.1 The criteria in Table 1 should be used to judge the acceptability a
48、t the 95 % probability level of the results obtained bythis test method. The criteria were derived from an Interlaboratory study of five samples analyzed in triplicate by five laboratories.Practice E691 was followed for the design and analysis of the data; the details are given inASTM Research Repor
49、t RR:D16-1033.15.2 RepeatabilityResults in the same laboratory should not be considered suspect unless they differ by more than the amountscalculated from the appropriate equations in Table 1. Results differing by less than “r” have a 95 % probability of being correct.15.3 ReproducibilityResults submitted by two laboratories should not be considered suspect unless they differ by more thanthe amounts calculated from the appropriate equations in Table 1. Results differing by less than “R” have a 95 % probability ofbeing correct.15.4 BiasSi
