1、Designation: D 3257 06Standard Test Methods forAromatics in Mineral Spirits by Gas Chromatography1This standard is issued under the fixed designation D 3257; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 These test methods cover the determination of et
3、hylben-zene and total eight-carbon (C8) and heavier aromatics in theconcentration range from 0.1 to 30 % in mineral spirits havinga distillation range from 149 to 210C (300 to 410F) asdetermined by Test Method D86. The procedures permit theidentification and calculation of concentrations of aromatic
4、components to 0.1 volume %.1.2 It is recognized by analytical chemists that a singlecolumn gas chromatography analysis of an unknown sample isrisky. In such cases, multiple and different analytical tech-niques must be used for absolutely positive identification, forexample, several different gas chr
5、omatography columns, gaschromatography/mass spectrometer, or gas chromatography/infrared, etc. In these test methods the material is known and isclearly defined.1.3 Oxygenated compounds, if present, may interfere andcause erroneous results. Such oxygenated compounds are notnormally present in minera
6、l spirits.1.4 Three test methods are covered as follows:1.4.1 Test Method A, measurement of ethylbenzene content,C8plus higher aromatics (except ethylbenzene), and totalaromatics by means of a single packed column gas chromato-graphic analysis.1.4.2 Test Method B, measurement of ethylbenzene content
7、by means of a rapid packed column gas chromatographicanalysis.1.4.3 Test Method C, measurement of ethylbenzene content,C8plus higher aromatics (except ethylbenzene) and totalaromatics by means of a capillary column gas chromatographicanalysis.1.5 The values stated in SI units are to be regarded as t
8、hestandard. The values given in parentheses are for informationonly.1.6 For purposes of determining conformance of an ob-served or a calculated value using this test method to relevantspecifications, test result(s) shall be rounded off “to the nearestunit” in the last right-hand digit used in expres
9、sing thespecification limit, in accordance with the rounding-off methodof Practice E 29.1.7 For hazard information and guidance, see the suppliersMaterial Safety Data Sheet.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibili
10、ty 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.2. Referenced Documents2.1 ASTM Standards:2D86 Test Method for Distillation of Petroleum Products atAtmospheric PressureE29 Practice for Using
11、 Significant Digits in Test Data toDetermine Conformance with SpecificationsE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty ChemicalsE 260 Practice for Packed Column Gas Chromatography2.2 ASTM Adjuncts:D2PP Determination of Precision
12、and Bias Data33. Summary of Test Methods3.1 The material, with an internal standard, is introducedinto a gas chromatographic column containing a strongly polarliquid phase. The polar phase has very little affinity forsaturated and olefinic hydrocarbons while exhibiting a pro-nounced retention of aro
13、matics. This selectivity, which isillustrated in Fig. 1, results in the elution of all saturated andolefinic hydrocarbons in the products described above prior tothe elution of toluene. Either a thermal conductivity or flameionization detector may be used. Calibration is obtained in TestMethod A and
14、 C from a synthetic blend of the most important1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.35 on Solvents, Plasticizers, and ChemicalIntermediates.Current edition a
15、pproved April 1, 2006. Published April 2006. Originallyapproved in 1973. Last previous edition approved in 2001 as D 3257 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
16、refer to the standards Document Summary page onthe ASTM website.3Available from ASTM International Headquarters. Order Adjunct No.ADJD6300.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
17、2959, United States.aromatic compounds. Internal standards are used in all threetest methods. Typical chromatograms are shown in Fig. 2 andFig. 3.NOTE 1Refer to Practice E 260 for additional information on gaschromatography techniques.4. Significance and Use4.1 These test methods were developed to m
18、easure the typesand amounts of aromatics in mineral spirits to determinecompliance with air pollution regulations that restrict thearomatic content of solvents. They have been demonstrated tobe workable and to produce accurate results. However, due tothe sensitivity of the tests to operating variabl
19、es, some labora-tories having limited experience with gas chromatographicanalyses of hydrocarbons may experience difficulty in perform-ing the tests.TEST METHOD AETHYLBENZENE AND TOTALAROMATICS CONTENTS BY MEANS OF A SINGLEPACKED COLUMN GAS CHROMATOGRAPHICANALYSIS5. Apparatus5.1 Chromatograph, any g
20、as chromatographic instrumentthat has the following performance and characteristics:FIG. 1 Typical Resolution of Test Blend Using Packed ColumnFIG. 2 Typical Packed Column Chromatogram of Mineral Spirits (Column and Conditions Described in Table 2)D32570625.1.1 SensitivityThe overall sensitivity mus
21、t be sufficientto detect 0.1 volume % of any aromatic compound of interestwith a peak height of at least 10 % of full-scale chart deflectionwithout loss of resolution as defined in 5.1.2, or 10 times thenoise level.5.1.2 ColumnAny column and conditions may be usedprovided the system meets all the fo
22、llowing criteria when thetest blend is injected into the chromatograph and the chromato-gram recorded in accordance with 7.2, is analyzed as follows:5.1.2.1 Construct tangents to the peak to intersect thebaseline for the n-tridecane (nC13) and toluene peaks. Measurethe distance between the two peaks
23、 and the width of each peakas the distance along the baseline under the peak between thepoints of intersection (see Fig. 1).5.1.2.2 Calculate the peak resolution,R 5 2Dd / Y11 Y2! (1)where:Dd = distance between nC13and toluene peaks,Y1= width of nC13peak along the baseline, andY2= width of the tolue
24、ne peak along the baseline.The peak resolution, R, must be not less than 0.9, otherwisethe resolution of ethylbenzene may be lost.NOTE 2The selectivity of the column (separation of the nonaromaticsfrom aromatics) can be increased by increasing the concentration of liquidphase or by increasing the te
25、mperature of the chromatographic column.The resolution of the aromatic compounds can be improved by increasingthe length of the column or by decreasing the oven temperature or inletpressure of the carrier gas.5.1.2.3 Ethylbenzene must be separated from paraxyleneand isopropylbenzene or from paraxyle
26、ne plus isopropylben-zene with the depth of the valley after ethylbenzene not lessthan 50 % of the ethylbenzene peak height.5.1.2.4 The system must measure durene with a peak heightof at least 10 % of full scale chart deflection or at least 10 timesthe noise level.NOTE 3A combination of column mater
27、ials and conditions that hasbeen found to be particularly suitable for this test method is listed in Table1. Such column may be obtained from most chromatography supplyhouses that offer packed GC columns.5.2 Strip Chart Recorder Integrator A recording potenti-ometer with a fullscale deflection of 10
28、 mV or less should beused. If manual integration, such as triangulation, paper cut-outor planimeter, is employed the chart speed should be at least1.5 m/h (60 in./h) in order to minimize errors in peak areameasurement. This is not necessary where a ball-and-disk or anelectronic integrator is employe
29、d.5.3 Electronic IntegrationAny electronic data processingsystem or integration device, or both, may be used to determinethe areas of the chromatographic peaks.5.4 Micro SyringeA 10-L micro syringe for specimenintroduction.6. Reagents and Materials6.1 Aromatic HydrocarbonsToluene, ethylbenzene, par-
30、axylene, isopropylbenzene (cumene), 1,2,4-trimethylbenzene(pseudocumene), and 1,2,4,5-tetramethylbenzene (durene)99.5 mol % minimum.6.2 Carrier Gas (Note 3).6.3 Internal StandardCyclohexanone, 99.5 mol % mini-mum (see 1.7).6.4 Chromatographic Column (Note 3).6.5 Normal Paraffn nTridecane, 99.5 mol %
31、 minimum.6.6 Solid Support (Note 3).6.7 Paraffn Solvent for Test Blendn-Hexane, n-heptane,or iso-octane 99 mol % minimum.7. Calibration7.1 Preparation of Test BlendPrepare a test blend toevaluate the sensitivity and resolution of the equipment and testprocedure. To do this, pipet the exact volume of
32、 each hydro-carbon indicated in Table 2 into a 100-mL volumetric flask. Fillto the 100-mL mark with one of the solvents listed in 6.7 andmix by inverting several times. See 1.7.NOTE 4Durene is a solid. In preparing the test blend, the quantity ofdurene required should be weighed, using as its densit
33、y 0.8875 g/mL.FIG. 3 Typical Capillary Chromatogram of Mineral Spirits(Column and Conditions Described in Table 3)TABLE 1 Typical Column and ConditionsLength, m 3.7 (12 ft)Diameter, mm:Inside .Outside 3.2 (18 in.)Liquid phase CEFAWeight % liquid 25Solid support: calcined pink, diatomaceous silicaBMe
34、sh 80100Treatment noneInlet, C 250Detector, C 250Column, C 110Carrier gas heliumInlet pressure, KPa 550 (80 psi)Flow rate, mL/min 35Detector flame ionizationRecorder, mV 1Specimen, L 2Sample split (30 to 1)AN,N-bis (2-cyanoethyl) formamide.BThe sole source of supply of the material Chromosorb-P know
35、n to thecommittee at this time is Celite Corp. If you are aware of alternative suppliers,please provide this information to ASTM International Headquarters. Your com-ments will receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.D32570637.2 Select t
36、he instrument conditions and specimen size so asto give the necessary sensitivity and resolution. Inject the testblend into the column at these conditions. Change the attenu-ation, if necessary, so that the internal standard and aromaticpeaks are measured with a chart deflection of not less than25 %
37、 nor more than 95 % of full scale for attenuated peaks.Check the column performance against the requirements givenin 5.1.2.7.3 Response FactorAssume that the aromatics in thesample have the same relative response as pseudocumene inthe test blend. Using the results from the test blend, calculatethe r
38、esponse factor as follows:r 5AISVIS3VaAa(2)where:r = relative response factor for aromatics,AIS= area of the internal standard peak in arbitrary unitscorrected for attenuation,VIS= volume % of the internal standard in the blend,Aa= area of the pseudocumene peak in arbitrary unitscorrected for attenu
39、ation, andVa= volume % of pseudocumene in the blend.8. Procedure8.1 Using the exact instrument conditions as were used inthe calibration, inject the test material. Inspect the chromato-gram to determine that there is complete resolution between thesaturated and the aromatic peaks.8.2 Pipet exactly 1
40、.0 mL of cyclohexanone internal standardinto a 10-mL volumetric flask. Fill to the mark with the sampleand mix by inverting several times.8.3 With the exact instrumental conditions used in thecalibration, inject the same volume of sample containing theinternal standard. Change the attenuation, if ne
41、cessary, so as tomeasure the area of the internal standard and aromatic peakswith not less than 25 % nor more than 95 % chart deflection onattenuated peaks.9. Calculation9.1 Measure the areas of all aromatic and internal standardpeaks. Use of an electronic integrator is recommended toobtain the best
42、 accuracy and precision.NOTE 5Because the C8and heavier aromatic compounds may not becompletely resolved, peak height multiplied by one half width or retentiontime must not be used as a means of measuring the area.9.2 If a different attenuation is used for part of the chro-matogram, correct to a con
43、stant attenuation basis by multiply-ing the area of the aromatic peaks by the ratio:Sa/ Ss(3)where:Ss= attenuation sensitivity used for the internal standardpeak andSa= attenuation sensitivity used for the aromatic peak.9.3 Calculate the concentrations of ethylbenzene and C8andheavier aromatics as f
44、ollows:Va5 Aa3 r 3 10!/AIS3 0.9! (4)5AaAIS3 r 3 11.11 (4)where:Va= volume % of the aromatic compound(s),Aa= area of the aromatic peak(s) corrected to a constantattenuation,r = relative response factor for the aromatic com-pounds,10 = volume % of internal standard,AIS= area of the internal standard p
45、eak, and0.9 = factor to correct for the dilution by the internalstandard.9.4 Total AromaticsAdd the amounts of the aromaticcompounds found to obtain the volume percent of totalaromatics in the sample.10. Report10.1 Report the following information: concentrations ofethylbenzene, total aromatics, and
46、 C8plus higher aromatics(except ethylbenzene) in volume percent to the nearest 0.1 %.11. Precision and Bias411.1 The precision estimates are based on an interlaboratorystudy on four samples, containing approximately 6.5, 8.5, 11.8,and 16.5 % total aromatics and 0.0, 1.0, 4.0, and 0.3 %ethylbenzene.
47、One analyst in each of six laboratories per-formed duplicate determinations on different days, for a total of48 determinations of total aromatics content and 48 determi-nations of ethylbenzene content. The within-laboratory coeffi-cient of variation was found to be 1.7 % relative with 23 df,and the
48、between-laboratories coefficient of variation was 4.4 %relative with 5 df. Based on these coefficients the followingcriteria should be used for judging the acceptability of resultsat the 95 % confidence level.11.1.1 RepeatabilityTwo results obtained by the sameoperator on different days should be co
49、nsidered suspect if theydiffer by more than 5 % relative.11.1.2 ReproducibilityTwo results obtained by operatorsin different laboratories should be considered suspect if theydiffer by more than 16 % relative.11.2 BiasThere was no statistically significant bias of theresults compared with expected values for quantitatively pre-pared standards. Hence, the determination of total aromatics in4Supporting data are available from ASTM International Headquarters. RequestRR:D01-1015.TABLE 2 Composition of Test BlendVolume, mLNormal tridecane from 6.5 1Tolu
