1、Designation: D5917 12D5917 15Standard Test Method forTrace Impurities in Monocyclic Aromatic Hydrocarbons byGas Chromatography and External Calibration1This standard is issued under the fixed designation D5917; the number immediately following the designation indicates the year oforiginal adoption o
2、r, in the 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 the total nonaromatic hydrocarbo
3、ns and trace monocyclic aromatichydrocarbons in toluene, mixed xylenes, and p-xylene by gas chromatography. The purity of toluene, mixed xylenes, or p-xylenecan also be calculated. Calibration of the gas chromatographic system is done by the external standard calibration technique. Asimilar test met
4、hod, using the internal standard calibration technique, is Test Method D2360.1.2 Total aliphatic hydrocarbons containing 1 through 10 carbon atoms (methane through decanes) can be detected by this testmethod at concentrations ranging from 0.001 to 2.500 weight %.1.2.1 A small amount of benzene in mi
5、xed xylenes or p-xylenes may not be distinguished from the nonaromatics and theconcentrations are determined as a composite (see 6.1).1.3 Monocyclic aromatic hydrocarbon impurities containing 6 through 10 carbon atoms (benzene through C10 aromatics) canbe detected by this test method at individual c
6、oncentrations ranging from 0.001 to 1.000 weight %.1.4 In determining the conformance of the test results to applicable specifications, results shall be rounded off in accordancewith the rounding-off method of Practice E29.1.5 The values stated in SI units are to be regarded as standard. No other un
7、its of measurement are included in this standard.1.6 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 safety and health practices and determine the applicability of reg
8、ulatorylimitations prior to use. For specific hazard statement, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D841 Specification for Nitration Grade TolueneD2360 Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas ChromatographyD3437 Practice for Sampling and Handl
9、ing Liquid Cyclic ProductsD4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density MeterD4307 Practice for Preparation of Liquid Blends for Use as Analytical StandardsD4790 Terminology of Aromatic Hydrocarbons and Related ChemicalsD5136 Specification for High Pu
10、rity p-XyleneD5211 Specification for Xylenes for p-Xylene FeedstockD6526 Test Method for Analysis of Toluene by Capillary Column Gas ChromatographyD6563 Test Method for Benzene, Toluene, Xylene (BTX) Concentrates Analysis by Gas ChromatographyD6809 Guide for Quality Control and Quality Assurance Pro
11、cedures for Aromatic Hydrocarbons and Related MaterialsE29 Practice for Using Significant Digits in Test Data to Determine Conformance with SpecificationsE260 Practice for Packed Column Gas ChromatographyE355 Practice for Gas Chromatography Terms and RelationshipsE691 Practice for Conducting an Inte
12、rlaboratory Study to Determine the Precision of a Test Method1 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 Their Derivatives.Curren
13、t edition approved Sept. 15, 2012Feb. 1, 2015. Published September 2102May 2015. Originally approved in 1996. Last previous edition approved in 20092012 asD5917 09.D5917 12. DOI: 10.1520/D5917-12.10.1520/D5917-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Cus
14、tomer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standardsstandards Document Summary page on the ASTM website.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
15、made 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.*
16、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 States1E1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs2.2 Other Document:OSHA Reg
17、ulations, 29 CFR paragraphs 1910.1000 and 1910.120033. Terminology3.1 See Terminology D4790 for definitions of terms used in this test method.3.2 Mixed xylenes are a mixture of C8 aromatics including m-xylene, o-xylene, and p-xylene. Industry convention includesethylbenzene as a mixed xylene though
18、ethylbenzene is not technically a xylene. Styrene is excluded.4. Summary of Test Method4.1 A repeatable volume of the specimen to be analyzed is precisely injected into a gas chromatograph equipped with a flameionization detector (FID). The peak area of each impurity is measured. Concentration of ea
19、ch impurity is determined from thelinear calibration curve of peak area versus concentration. Purity by gas chromatography (GC) is calculated by subtracting the sumof the impurities found from 100.00. Results are reported in weight percent.5. Significance and Use5.1 Determining the type and amount o
20、f hydrocarbon impurities remaining from the manufacture of toluene, mixed xylenes, andp-xylenes used as chemical intermediates and solvents is often required. This test method is suitable for setting specifications andfor use as an internal quality control tool where these products are produced or a
21、re used. Typical impurities are: alkanes containing1 to 10 carbons atoms, benzene, toluene, ethylbenzene (EB), xylenes, and aromatic hydrocarbons containing nine carbon atoms.5.2 Purity is commonly reported by subtracting the determined expected impurities from 100.00. However, a gas chromato-graphi
22、c analysis cannot determine absolute purity if unknown or undetected components are contained within the material beingexamined.5.3 This test method is similar to Test Method D2360, however, interlaboratory testing has indicated a bias may exist betweenthe two methods. Therefore the user is cautione
23、d that the two methods may not give comparable results.6. Interferences6.1 In some cases for mixed xylenes and p-xylene, it may be difficult to resolve benzene from the nonaromatic hydrocarbons.Therefore the concentrations are determined as a composite. In the event that the benzene concentration mu
24、st be determined, analternate method such as Test Method D6526 must be selected to ensure an accurate assessment of the benzene concentration.6.2 Complete separation of ethylbenzene and m-xylene from p-xylene is difficult and can be considered adequate if the distancefrom baseline to valley between
25、peaks is not greater than 50 % of the peak height of the impurity.7. Apparatus7.1 Gas ChromatographAny instrument having a flame ionization detector that can be operated at the conditions given inTable 1. The system shall have sufficient sensitivity to obtain a minimum peak height response for 0.001
26、 weight % impurity oftwice the height of the background noise.7.2 ColumnsThe choice of column is based on resolution requirements.Any column may be used that is capable of resolvingall significant impurities from the major component. The column and conditions described in Table 1 have been used succ
27、essfullyand shall be used as a referee in cases of dispute.7.3 RecorderElectronic integration is recommended.7.4 InjectorThe specimen must be precisely and repeatably injected into the gas chromatograph. An automatic sampleinjection device is highly recommended although manual injection can be emplo
28、yed if the criteria in 12.7 can be satisfied.7.5 Volumetric Flask, 100-mL capacity.7.6 Syringe, 100 L.8. Reagents8.1 Purity of ReagentReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee o
29、n Analytical Reagents of the American Chemical Society,4 wheresuch specifications are available.3 Available 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.4 Reagent Chemicals, American Chemical
30、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, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharm
31、acopeial Convention, Inc. (USPC), Rockville, MD.D5917 1528.2 Carrier GasChromatographic grade helium or hydrogen, 99.999 % is recommended. Purify carrier, fuel and makeupgases by adding traps to reduce the concentration of any remaining oxygen, water, and hydrocarbons. Purify air by adding trapsto r
32、educe the concentration of any remaining hydrocarbons and water.8.3 Air, Chromatographic grade, containing less than 0.1 ppm THC.8.4 High Purity p-Xylene, 99.999 weight % or greater purity.8.4.1 Most p-xylene is available commercially at a purity less than 99.9 % and can be purified by recrystalliza
33、tion. To prepare1.9 L of high purity p-xylene, begin with approximately 3.8 L of material and cool in a flammable storage freezer at 10 6 5Cuntil approximately 12 to 34 of the p-xylene has frozen. This should require about 5 h. Remove the sample and decant the liquidportion. The solid portion is the
34、 purified p-xylene. Allow the p-xylene to thaw and repeat the crystallization procedure on theremaining sample until the p-xylene is free of contamination as indicated by gas chromatography.8.5 Pure compounds for calibration, shall include n-nonane, benzene, toluene, ethylbenzene, o-xylene, m-xylene
35、, and cumene.If applicable, the calibration may include paradiethylbenzene (PDEB). The purity of all reagents should be 99 weight %. If thepurity is less than 99 %, the concentration and identification of impurities must be known so that the composition of the standardcan be adjusted for the presenc
36、e of the impurities.9. Hazards9.1 Consult current OSHA regulations, suppliers Material suppliers Safety Data Sheets, and local regulations for all materialsused in this test method.10. Sampling10.1 Sample the material in accordance with Practice D3437.11. Preparation of Apparatus11.1 Follow manufact
37、urers instructions for mounting and conditioning the column into the chromatograph and adjusting theinstrument to the conditions described in Table 1, allowing sufficient time for the equipment to reach equilibrium. See PracticesE260, E355, and E1510 for additional information on gas chromatography
38、practices and terminology.12. Calibration12.1 Prepare a synthetic mixture of high purity p-xylene containing impurities at concentrations representative of those expectedin the samples to be analyzed. The volume of each hydrocarbon impurity must be measured to the nearest 1 L and all liquidreference
39、 compounds must be brought to the same temperature before mixing. Refer to Table 2 for an example of a calibrationblend. n-Nonane will represent the nonaromatic fraction, o-xylene the o-xylene fraction, m-xylene the m-xylene fraction. Cumenewill represent the aromatic hydrocarbons containing nine ca
40、rbon atoms or greater, with exception of PDEB. If PDEB is includedin the calibration, PDEB will represent PDEB.12.1.1 Prior to preparing the calibration standard, all reference compounds and any samples to be analyzed must be brought tothe same temperature, preferably ambient or 20C.12.2 Using the e
41、xact volumes and densities in Table 2, calculate the weight % concentration for each impurity in the calibrationblend as follows:TABLE 1 Recommended Operating ConditionsInlet SplitTemperature, C 270Column:Tubing fused silicaLength, m 60Internal diameter, mm 0.32Stationary phase crosslinked polyethyl
42、ene glycolFilm thickness, m 0.25Column temperature programInitial temperature, C 60Initial time, min 10Programming rate, C/min 5Final, C 150Time 2, min 10Carrier gas Helium or HydrogenLinear velocity, cm/s at 145C 20 Helium or 45 HydrogenSplit ratio 100:1Sample size, L 1.0Detector: flame ionizationT
43、emperature, C 300Analysis time, min 30D5917 153Ci 5100 DiVi/VtDp! (1)where:Di = density of impurity i from Table 2,Vi = volume of impurity i, mL,Dp = density of p-xylene from Table 2,Vt = total volume of standard blend, mL, andCi = concentration of impurity i, weight %.where:Di = density of impurity
44、 i from Table 2,Vi = volume of impurity i, mL,Dp = density of p-xylene from Table 2,Vt = total volume of standard blend, mL, andCi = concentration of impurity i, weight %.12.2.1 Alternatively, calibration standards may be used that have been gravimetrically prepared in accordance with PracticeD4307.
45、12.3 Inject the resulting solution from 12.1 into the chromatograph, collect and process the data. A typical chromatogram isillustrated in Fig. 1.12.4 Determine the response factor for each impurity in the calibration mixture as follows:RFi 5Ci/Ai (2)where:RFi = response factor for impurity i,Ai = p
46、eak area of impurity i, andCi = concentration of impurity i, as calculated in 12.2, weight %.where:RFi = response factor for impurity i,Ai = peak area of impurity i, andCi = concentration of impurity i, as calculated in 12.2, weight %.12.5 Analyze the calibration solution(s) a minimum of three times
47、 and calculate an average RF.12.6 Determine the sample standard deviation for RF of each impurity using a scientific calculator or spreadsheet program.Determine the coefficient of variation for each RF as follows:TABLE 2 Preparation of Calibration BlendCompound DensityA RecommendedVol, LResulting Co
48、ncentration(including PDEB)Resulting Concentration(excluding PDEB)Volume % Weight % Volume % Weight %p-Xylene 0.861 99.60-99.62 ml 99.60 99.60 99.62 99.62Benzene 0.879 20 0.020 0.020 0.020 0.020Toluene 0.867 20 0.020 0.020 0.020 0.020Ethylbenzene 0.867 100 0.100 0.100 0.100 0.100o-Xylene 0.880 100 0
49、.100 0.102 0.100 0.102Cumene 0.862 20 0.020 0.020 0.020 0.020n-Nonane 0.718 20 0.020 0.017 0.020 0.017m-Xylene 0.864 100 0.100 0.101 0.100 0.101PDEB 0.866 20 0.020 0.020 n/a n/aTABLE 2 Preparation of Calibration BlendCompound DensityA RecommendedVol, LResulting Concentration (includingPDEB)Resulting Concentration (excludingPDEB)Volume % Weight % Volume % Weight %p-Xylene 0.861 99.60-99.62 ml 99.60 99.60 99.62 99.62Benzene 0.879 20 0.020 0.020 0.020 0.020Toluene 0.867 20 0.020 0.020 0.020 0.020Ethylbenzene 0.867 100 0.100 0.100 0.100 0.100o-Xylene
