7.1Mid-IRSpectrometricAnalyzer(ofoneofthefollowingtypes):
7.1.1Filter-basedMid-IRTestApparatus—ThetypeofapparatussuitableforuseinthistestmethodminimallyemployesanIRsource,aninfraredtransmissioncelloraliquidattenuatedtotalinternalreflectioncell,wavelengthdiscrimi-natingfilters,achopperwheel,adetector,anA-Dconverter,amicroprocessor,andamethodtointroducethesample.ThefrequenciesandbandwidthsofthefiltersarespecifiedinTable1.
7.1.2FourierTransformMid-IRSpectrometer—ThetypeofapparatussuitableforuseinthistestmethodemploysanIRsource,aninfraredtransmissioncelloraliquidattenuatedtotalinternalreflectioncell,ascanninginterferometer,adetector,anA-Dconverter,amicroprocessor,andamethodtointroducethesample.Thefollowingperformancespecifications(throughtheATRcell)mustbemet:
scanrange4000to600cm–1resolution
4cm–1S/Nat674cm–1>300:1RMS
Thesignaltonoiselevelwillbeestablishedbytakingasinglebeamspectrumusingairornitrogenasthereferenceanddeclaringthatspectrumasthebackground.ThebackgroundsinglebeamspectrumobtainedcanbetheaverageofmultipleFTIRscans,butthetotalcollectiontimeshallnotexceed60s.Ifinterferencefromwatervapororcarbondioxideisaproblem,theinstrumentshallbepurgedwithdryairornitrogen.Asubsequentsinglebeamspectrumshallbetakenunderthesameconditionsandratioedtothebackgroundspectrum.TheRMSnoiseoftheratioedspectra,the100%line,shallnotexceed0.3%transmittanceintheregionfrom700to664cm–1.
7.2AbsorptionCell—Theabsorptioncellcanbeeithertransmissionorattenuatedtotalreflectance.
7.2.1TransmissionCells,shallhavewindowsofpotassiumbromide,zincselenide,orothermaterialhavingasignificanttransmissionfrom712cm–1to660cm–1.Thecellpathlengthofthetransmissioncellshallbe0.025(+/–0.005)mm.Theuseofawedgedtransmissioncellwiththesamenominalpathlengthisacceptable.
7.2.2AttenuatedTotalReflectance(ATR)Cells,shallhavethefollowingspecifications:
TABLE1SpecificationforFiltersUsedinFilter-basedMid-IR
Test
CenterWavenumberBandwidth(inwavelengthunits)
(+/−0.15%ofwavenumber)
(fullwidthathalfheight)
673cm-11%oflc729cm-11%oflc769cm-11%oflc1205cm-11%oflc1054cm-11%oflc1188cm-11%oflc1117cm-11%
oflcATRelementmaterialZnSe
beamcondensingopticsconical,non-focussingopticsintegraltocellbody
elementconfigurationcircularcrosssectionwithcoaxialconicalendsconehalfangle60°elementlength1.55in.elementdiameter0.125in.angleofincidenceatsampleinterface53.8°maximumrangeofincidenceangles+/–1.5°
standardabsorbance
(1428cm−1bandofacetone)0.38+/–0.02AUmaterialofconstruction316stainlesssteel
seals
ChemrazorKalrazo-rings
8.ReagentsandMaterials(seeNote1andNote2)
8.1StandardsforCalibration,Qualification,andQualityControlCheckStandards—Useofchemicalsofatleast99%purity,whereavailable,forqualitycontrolchecksisrequiredwhenpreparingsamples.
8.1.1tert-Amylmethylether,TAME[994-05-8].8.1.2Benzene[1076-43-3].
8.1.3tert-Butylethylether,ETBE[637-92-3].8.1.4tert-Butylmethylether,MTBE[1634-04-4].8.1.51,3Dimethylbenzene(m-xylene).8.1.6Ethanol[64-17-5].
8.1.7Ethylbenzene[100-41-4].8.1.83–Ethyltoluene[620-14-4].
8.1.9Heavyaromatic/reformatepetroleumstream(highboilingcut:IPBof150+/−5°CandEPof245+/−8°C)certifiedtocontainlessthan0.025%benzene(anabsorbanceoflessthan0.03at675cm−1using−1a0.2mmcellandabaselinebetweenapproximately680cmand670cm−1)[64741-68-0].8.1.10Hexane(anabsorbanceversuswateroflessthan0.1at250nmusinga1cmcell)[110-54-3].
8.1.112,2,4-Trimethylpentane(isooctane)[540-84-1].
8.1.12Pentane(anabsorbanceversuswateroflessthan0.1at250nmusinga1cmcell)[109-66-0].8.1.13Propylbenzene[103-65-1].8.1.14Toluene[108-88-3].
8.1.151,3,5-Trimethylbenzene(mesitylene)[108-67-8].8.1.16m-Xylene[108-38-3].
NOTE1—Warning:Thesematerialsareflammableandmaybeharmfulifingestedorinhaled.
NOTE2—Onlysomeofthereagentsarerequiredineachcalibrationorqualificationprocedure.
9.SamplingandSampleHandling9.1GeneralRequirements:
9.1.1Thesensitivityofthemeasurementofbenzenetothelossofbenzeneorothercomponentsthroughevaporationandtheresultingchangesincompositionissuchthattheutmostprecautionandthemostmeticulouscareinthedrawingandhandlingofsamplesisrequired.
9.1.2FuelsamplestobeanalyzedbythetestmethodshallbesampledusingproceduresoutlinedinPracticesD4057,D4177,orD5842,whereappropriate.Donotusethe“Sam-plingbyWaterDisplacement.”Withsomealcoholcontainingsamples,thealcoholwilldissolveinthewaterphase.
9.1.3Protectsamplesfromexcessivetemperaturespriortotesting.Thiscanbeaccomplishedbystorageinanappropriate
icebathorrefrigeratorat0to5°C.
9.1.4Donottestsamplesstoredinleakycontainers.Discardandobtainanewsampleifleaksaredetected.9.2SampleHandlingDuringAnalysis:
9.2.1Whenanalyzingsamplesbythemidinfraredappara-tus,thesamplemustbebetweenatemperatureof15to38°C.Equilibrateallsamplestothetemperatureofthelaboratory(15to38°C)priortoanalysisbythistestmethod.
9.2.2Afteranalysis,ifthesampleistobesaved,resealthecontainerandstorethesampleinanicebathorarefrigeratorat0to5°C.
10.CalibrationandStandardizationoftheApparatus10.1CalibrationMatrix—Calibrationstandardsshallbe
preparedinaccordancewithPracticeD4307orappropriatelyscaledforlargerblendsandPracticesD5842andD5854,whereappropriate.Wheneverpossible,usechemicalsofatleast99%purity.Tominimizetheevaporationoflightcomponents,chillallchemicalsandfuelsusedtopreparestandards.
10.1.1CalibrationMatrixforFilterBasedMidIRInstruments—Preparethesetofcalibrationstandardsasde-finedinTable2.
TABLE2FilterBasedMidIRInstrumentCalibrationSampleSet(mass%)
Sample1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253
Benzene0.000.000.000.000.000.000.000.250.250.250.250.250.500.500.500.500.500.500.750.750.750.750.751.001.001.001.001.001.001.501.501.501.501.502.002.002.002.002.002.502.502.502.502.503.003.003.003.003.004.004.004.004.00
Toluene2.502.505.0012.520.025.025.00.002.504.7510.014.02.505.006.0010.012.525.05.0010.012.512.525.015.005.007.5010.015.025.05.0015.015.010.025.05.005.0012.525.025.00.005.0015.010.020.05.0010.015.020.025.00.002.5015.020.0
Xylenes12.525.07.5012.510.07.502.5010.06.0015.00.007.5012.510.07.5015.04.0010.025.010.00.0012.520.025.07.5010.010.02.0020.015.015.015.05.0010.07.5020.012.55.0020.015.05.000.0015.020.025.015.05.0020.010.020.05.002.5015.0
Hvy.Ref.A5.002.5010.03.001.002.507.505.002.501.0010.03.005.002.007.502.507.501.001.005.0010.01.0010.01.0010.07.505.002.50.005.001.001.007.500.002.500.005.003.000.002.5010.07.502.53.005.005.002.005.002.002.5010.05.002.00
MTBE0.000.001.0020.00.000.000.000.000.000.0015.000.005.000.000.000.000.000.000.000.000.000.000.007.500.0020.000.0015.00.005.000.000.000.000.007.500.000.0020.000.000.0015.00.000.000.000.000.002.500.000.000.005.002.000.00
EtOH00.00.000.000.0010.000.004.000.000.007.500.005.000.000.000.0012.50.000.000.000.005.000.000.000.002.000.0010.00.000.000.000.000.007.500.000.000.008.000.000.000.000.0010.00.000.000.007.500.000.000.005.000.0010.00.00
TAME20.00.002.502.500.000.000.000.000.000.000.000.005.000.0020.00.000.000.000.000.000.000.000.0015.00.000.000.002.500.0010.005.000.000.000.002.500.000.000.000.0015.00.000.000.000.007.500.0010.00.000.000.005.002.000.00
ETBE0.000.0015.00.000.000.000.0020.000.000.000.000.005.000.000.000.0020.00.000.000.000.000.000.002.500.000.000.007.500.005.0020.00.002.500.002.000.000.000.000.000.000.000.0015.00.007.507.502.500.000.000.005.000.000.00
Isooctane30.035.025.025.025.040.020.025.035.025.030.030.020.030.025.025.020.025.030.030.035.030.014.2510.035.020.030.020.025.020.020.030.025.025.030.030.025.0020.020.025.025.030.025.025.020.020.025.025.030.025.025.020.025.0
C5C6B30.035.034.024.534.025.041.039.7553.7546.5034.7540.2544.542.533.534.535.538.538.2544.2536.7543.2530.023.039.534.034.037.029.033.522.537.541.038.541.043.035.025.033.040.037.535.030.029.527.032.035.027.030.043.538.539.534.0
TABLE2ContinuedSample54555657585960
Benzene4.005.005.005.005.005.005.00
Toluene25.05.007.5012.520.020.025.0
Xylenes20.025.005.0012.55.002.5020.0
Hvy.Ref.A1.004.007.502.505.002.500.00
MTBE0.000.000.0015.00.000.000.00
EtOH0.000.000.000.005.000.000.00
TAME0.000.000.000.000.007.500.00
ETBE0.000.0015.00.000.000.000.00
Isooctane25.025.025.020.025.025.020.0
C5C6B25.036.035.032.535.037.530.0
AHeavyreformatepetroleumstreamB50volume%pentaneinhexane
10.1.1.1MeasurethedensityforeachofthecalibrationstandardsaccordingtoeitherPracticeD1298orTestMethodD4052.
10.1.1.2Foreachofthecalibrationstandards,convertthemass%benzenetovolume%benzeneaccordingtotheequationpresentedin13.1.
10.1.2CalibrationMatricesforFTIRInstrumentsUsingaPLSCalibration—Toobtainthebestprecisionandaccuracyofcalibration,preparetwobenzenecalibrationsetsassetforthinTable3andTable4.Thefirstset(SetA)has35sampleswithbenzeneconcentrationsbetween0to1.5mass%.Thesecondset(SetB)hasatleast25sampleswithbenzeneconcentrationsbetween1to6mass%.EachofthesubsetsinSetBshallhaveaminimumoffivesampleswiththebenzeneconcentrationevenlyspacedoverthe1to6mass%range.
10.1.2.1Measurethedensityforeachofthecalibration
TABLE3FTIRInstrumentsPLSCalibrationSampleSetA
(mass%)
SampleBenzeneTolueneMixedXylenesIsoctane(mass%)(mass%)(mass%)
(mass%)100
0100207093301408640210795015157060.250099.7570.50099.580.750099.25910099101.250.098.75111.50098.5120.257092.75130.57092.5140.757092.251517092161.257091.75171.57091.5180.2514085.75190.514085.5200.7514085.2521114085221.2514084.75231.514084.5240.2521078.75250.521078.5260.75210.78.2527121078281.2521077.75291.521077.5300.25151569.75310.5151569.5320.75151569.25331151569341.25151568.7535
1.5
15
15
68.5
TABLE4FTIRInstrumentsPLSCalibrationSampleSetB
(mass%)
Subset(minimum5BenzeneTolueneMixedsamples)(mass%)(mass%)XylenesIsooctaneineachsubset)
(mass%)(mass%)Subset11–600to100%Subset21–67–90to100%Subset31–614–170to100%Subset41–621–250to100%Subset
5
1–6
15–18
15–18
to100%
standardsaccordingtoeitherPracticeD1298orTestMethodD4052.
10.1.2.2Foreachofthecalibrationstandards,convertthemass%benzenetovolume%benzeneaccordingtotheequationpresentedin13.1.Ifthedensitiesofthecalibrationstandardscannotbemeasured,itisacceptabletoconverttovolume%usingthedensitiesoftheindividualcomponentsmeasuredusingPracticeD1298orTestMethodD4052.10.1.3CalibrationMatrixforFTIRInstrumentsUsingClassicalLeastSquaresPeakFittingCalibration—PrepareabenzenecalibrationsetasdetailedinTable5.Thesethassampleswithbenzeneconcentrationsbetween0to6mass%.10.1.4BackgroundCorrectionMixturesforFTIRInstru-mentsUsingClassicalLeastSquaresPeakFittingCalibration—Prepareonemixturecontaining80mass%hexaneand20mass%oftherespectivearomaticforeachofthesixsubstances(toluene,1,3-dimethylbenzene,3–ethyltoluene,1,3,5-trimethylbenzene,ethylbenzene,andpropylbenzene)assetforthinTable6.
TABLE5FTIRInstrumentsCalibration(ClassicalLeastSquares
PeakFitting)SampleSet(mass%)
SampleBenzeneTolueneIsooctane1059520158530.5594.540.51584.55159461158471.5593.581.51583.592593102158311359212315821345911441581155590165158017658918
6
15
79
TABLE6FTIRBackgroundCorrectionMixtures(ClassicalLeast
SquaresPeakFitting)
1,31,3,5-Dimethyl-3-Ethyl-trimethyl-Ethyl-Propyl-SampleHexaneToluene
benzenetoluenebenzenebenzenebenzene(mass(mass(mass(mass(mass(mass(mass%)%)%)%)%)%)%)180200000028002000003800020000480000200058000002006
80
0
0
0
0
0
20
10.2Calibration:
10.2.1EachinstrumentmustbecalibratedinaccordancewiththemathematicsasoutlinedinPracticeE1655.Thispracticeservesasaguideforthemultivariatecalibrationofinfraredspectrometersusedindeterminingthephysicalchar-acteristicsofpetroleumandpetrochemicalproducts.Theproceduresdescribetreatmentofthedata,developmentofthecalibration,andqualificationoftheinstrument.PLSoraclassicalleastsquarespeakfittingcalibrationmaybeusedifacontinuousfrequencyregion(s)ofthespectrumisacquired,andMLRmaybeusedifabsorbancesatdiscretefrequenciesareused.
10.2.2Equilibrateallsamplestothetemperatureofthelaboratory(15to38°C)priortoanalysis.FillthesamplecellwiththecalibrationstandardsinaccordancewithPracticeE168orinaccordancewiththemanufacturer’sinstructions.10.2.3Foreachofthecalibrationstandards,acquireeitherthedigitizedspectraldataortheabsorbancesthrougheachspecifiedfilter.
10.2.3.1IfafilterbasedmidIRinstrumentisbeingused,acquiretheabsorbancesatthewavelengthscorrespondingtothespecifiedfiltersforeachofthecalibrationstandards.
10.2.3.2IfanFTIRisbeingused,acquirethedigitizedspectral–1dataoverthefrequencyregionfrom4000cm–1to600cmforeachofthecalibrationstandards.TheinfraredspectrumisthenegativelogarithmoftheratioofthesinglebeaminfraredspectrumobtainedwithasampleandthesinglebeamFTIRspectrumwithdryair(ornitrogen).ForFTIRinstrumentsusingaPLScalibration,baselinecorrectthespectrumusingalinearbaseline–1fittoabsorbancesmeasuredbetween712and658cm.
10.2.4ForfilterbasedmidIRinstruments,developacalibrationmodelbasedonthecorrelationofthesetofcalibrationspectratoknownbenzeneconcentrations(volume%)accordingtoPracticeE1655byfittingtothefollowingMLRequation:
C5a@x#1······1anxn1b1x673cm–121b2x729
cm–1
21e(1)
where:C5concentrationoftheanalyte,volume%,axnandbn5theregressedcoefficients,en55thetheabsorbanceintercept.
atfilterwavelength,n,and10.2.5ForFTIRinstrumentsusingaPLScalibration,twoseparatecalibrationswillbedeveloped.
10.2.5.1Developthefirstcalibration(usingsamplesovertherangeof0to1.5mass%),referredtoasthelowcalibration,
usingspectraobtainedfromthesamplesincalibrationSetAdetailedinTable3.Thiscalibrationrelatesthespectrumtothebenzeneconcentration(volume%).Usebaselinecorrecteddataintheregionof712to664cm–1todevelopthelowcalibration.Usemeancenteringandfourlatentvariablesindevelopingthemodel.
10.2.5.2Developthesecondcalibration(usingsamplesovertherange1to6.0mass%),referredtoasthehighcalibration,usingspectraobtainedfromallofthesamplesincalibrationSetBasdetailedinTable4.Thiscalibrationrelatesthespectrumtothebenzeneconcentration(volume%).Usebaselinecor-recteddataintheregionof712to664cm–1todevelopthehighcalibration.Usemeancenteringandfourlatentvariablesindevelopingthemodel.
10.2.6ForFTIRinstrumentsusingaclassicalleastsquarespeakfittingcalibrationasinglecalibrationwillbedeveloped.Thiscalibrationrelatesthespectrumtothebenzeneconcen-tration(mass%).Inthecalibration,thespectraintheregionof710through660cm–1areusedindevelopingthecalibrationmodel.
10.2.6.1Measurethespectraofthesixbackgroundcorrec-tionmixturesasdetailedinTable6aswellasthespectrumofpurehexaneintheregionof710through660cm–1.Foreachofthemixturespectra,subtract0.80timesthespectrumofhexanefromthespectrumofthe20mass%solution.Theresultingspectrumisthederivedspectrumoftherespectivearomatic.
10.2.6.2Fittheabsorptionspectrumintheregionof710through660cm–1usingaclassicalleastsquaresfit(k-matrixmethod).Thefitmatrixmustincludethederivedspectraoftoluene,1,3-dimethylbenzene,3-ethyltoluene,1,3,5-trimethylbenzene,ethylbenzene,andpropylbenzene.
10.2.6.3Toeliminatespectraloverlaps,subtractthederivedspectraoftoluene,1,3-dimethylbenzene,3-ethyltoluene,1,3,5-trimethylbenzene,ethylbenzeneandpropylbenzene,multipliedbythecoefficientsthatresultedfromtheclassicalleastsquaresfittotheabsorptionspectrum.Inthisway,aresidualbenzenepeakisobtained.
10.2.6.4FittheresidualbenzenepeakwithaLorentzianlineshapefunctionwithalinearbackgroundintheregionof691through660cm–1.ThefollowingequationisusedfortheLorentzianlineshapefunctionL(v):
L~n!5AG2/@G21~n0–n!2#1kn1d
(2)
where:
AG5n5peakhalfwidth,
height,n05centerwavenumber,k55wavenumber,
slopeoflinesbackground,andd5interceptoflinearbackground.
ThefitparametersfortheleastsquaresfitareA,G,n0,k,andd.
10.2.6.5Developthecalibrationequationusingthepeakheightoftheresidualpeak(parameterAversusmass%benzene).
10.3QualificationofInstrumentPerformance—Onceacalibration(s)hasbeenestablished,theindividualcalibratedinstrumentmustbequalifiedtoensurethattheinstrument
accuratelyandpreciselymeasuresbenzeneinthepresenceoftypicalspark-ignitionenginefuelcompoundsthat,intypicalconcentrations,presentspectralinterferences.Generalclassesofcompoundsthatwillcauseinterferencearemonosubstitutedaromatics(forallofthecalibrationprocedures)andoxygenates(forcalibrationusingfilterinstruments)inhighconcentrations.Thisqualificationneedonlybecarriedoutwhentheinstrumentisinitiallyputintooperation,isrecalibrated,orrepaired.10.3.1PreparationofQualificationSamples—Preparemul-ticomponentqualificationstandardsofthebenzenebymassaccordingtoPracticesD4307(orappropriatelyscaledforlargerblends),PracticeD5842orD5854,whereappropriate.Thesestandardsshallbesimilarto,butnotthesameas,themixturesestablishedforthecalibrationsetusedindevelopingthecalibration.Preparethequalificationsamplessoastovarytheconcentrationsofbenzeneandoftheinterferingcompo-nentsoverarangethatspansatleast95%ofthatforthecalibrationstandards.ThenumbersofrequiredstandardsaresuggestedbyPracticeE1655and,ingeneral,willbefivetimesthenumberofindependentvariablesinthecalibrationequa-tion.ForafourcomponentPLSmodel,aminimumof20qualificationstandardsarerequired.Forasevenfilterinstru-mentusingEq1forcalibration,50qualificationstandardsarerequired.Forcalibrationtechniquesthatrelyonaclassicalleastsquarespeakfittingtechnique,aminimumof20qualifi-cationstandardsarerequired.
10.3.2AcquisitionofQualificationData—Foreachofthequalificationstandards,measurethebenzeneconcentration,expressedinvolume%,accordingtotheprocedureestablishedinSection12.TheinstrumentperformanceissatisfactoryiftheStandardErrorofValidationforthesetofqualificationstandards(asdefinedinPracticeE1655)isequaltoorlessthan0.12.
11.QualityControlChecks
11.1Confirmthecalibrationoftheinstrumenteachdayitisusedbymeasuringthebenzeneconcentrationusingtheproce-dureoutlinedinSection12onatleastonequalitycontrolsampleofknownbenzenecontent.Thepreparationofknownbenzeneconcentrationisdescribedin11.1.1and11.1.2.
11.1.1Standard(s)ofknownbenzeneconcentrationshallbemadeupbymassaccordingto10.1andconvertedtovolume%usingthemeasureddensityasoutlinedinSection13.Atleastonestandardshallbemadeupat1.2(+/–0.2)mass%benzene,thatis,nominally1.0volume%.Additionalstandardsmayalsobepreparedandusedforqualitycontrolchecks.
11.1.2Standard(s)shouldbepreparedinsufficientvolumetoallowforaminimumof30qualitycontrolmeasurementstobemadeononebatchofmaterial.Packageorstore,orboth,qualitycontrolsamplestoensurethatallanalysesofqualitycontrolsamplesfromagivenlotareperformedonessentiallyidenticalmaterial.
11.2Ifthebenzenevolume%valueestimatedforthequalitycontrolsamplepreparedat1.2mass%benzenediffersfromtheknownvaluebymorethan0.12volume%,thenthemeasurementsystemisout-of-controlandcannotbeusedtoestimatebenzeneconcentrationsuntilthecauseoftheout-of-controlbehaviorisidentifiedandcorrected.
11.3Ifcorrectionofout-of-controlbehaviorrequiresrepair
totheinstrumentorrecalibrationoftheinstrument,thequalificationofinstrumentperformancedescribedin10.3shallbeperformedbeforethesystemisusedtomeasurebenzenecontentonsamples.
12.Procedure
12.1Equilibratethesamplestobetween15and38°Cbeforeanalysis.
12.2Cleanthesamplecell.Ifaseparatebaselineusingtheemptycellisrequired,andifresidualfuelisinthesamplecell,removethefuelbyflushingthecellandinlet-outletlineswithenoughpentanetoensurecompletewashing.Evaporatetheresidualpentanewitheitherdryairornitrogen.
12.3Ifneeded,obtainabaselinespectruminthemannerestablishedbythemanufactureroftheequipment.
12.4Priortotheanalysisofunknowntestsamples,establishthattheequipmentisrunningproperlybycollectingthespectrumofthequalitycontrolstandard(s),byanalyzingthespectrumwiththecalibrationmodel,andbycomparingtheestimatedbenzeneconcentrationtotheknownvaluefortheQCstandard(s).Introduceenoughstandardtothecelltoeinsurethatthecelliswashedaminimumofthreetimeswiththestandardsolution.
12.5Introducetheunknownfuelsampleinthemannerestablishedbythemanufacturer.Introduceenoughofthefuelsampletothecelltoensurethecelliswashedaminimumofthreetimeswiththefuel.
12.6Obtainthespectralresponseofthefuelsample.
12.6.1IfafilterbasedmidIRinstrumentisused,acquiretheabsorbanceforthefuelsampleatthewavelengthscorrespond-ingtothespecifiedfilters.
12.6.2IfanFTIRisused,acquirethedigitizedspectraldataforthefuel–1sampleoverthefrequencyregionfrom4000cm–1to600cm.
12.7Determinethebenzeneconcentration(volume%)ac-cordingtotheappropriatecalibrationequationdevelopedinSection10.
12.7.1ForfilterbasedmidIRinstruments,applythecali-brationequationdeterminedin10.2.4toconverttheabsor-bancesateachofthewavelengthstothebenzeneconcentrationexpressedinvolume%.
12.7.2ForFTIRinstrumentsusingaPLScalibration,deter-minethebenzeneconcentrationusingthecalibrationmodelsdevelopedin10.2.5byfollowingthestepsoutlinedasfollows.12.7.2.1Baselinecorrectthespectrumusingalinearbase-linefittoabsorbancesmeasuredbetween712and658cm–1.12.7.2.2Estimatethebenzeneconcentrationinthefuelsamplebyapplyingthelowcalibration(see10.2.5.1)tothebaselinecorrectedspectrumintheregionof712to664cm–1.12.7.2.3Iftheestimatedbenzeneconcentration(determinedin12.7.2.2)isequaltoorlessthan1.30volume%,determinethebenzeneconcentrationbyapplyingthelowcalibration(see10.2.5.2)tothebaselinecorrectedspectrumintheregionof712to664cm–1.
12.7.2.4Iftheestimatedbenzeneconcentration(determinedin12.7.2.2)isgreaterthan1.30volume%,estimatethebenzeneconcentrationbyapplyingthehighcalibration(see10.2.5.3)tothebaselinecorrectedspectrumintheregionof712to664cm–1.
12.7.2.5Ifthevalueestimatedbyapplicationofthehighcalibration(determinedin12.7.2.4)islessthanorequalto1.30volume%,reportthevaluedeterminedbythelowcalibration(evenifthevalueisgreaterthan1.30volume%).Forestimatedvaluesgreaterthan1.30volume%(determinedin12.7.2.4),reportthevalueobtained.
12.7.3ForFTIRinstrumentsusingaclassicalleastsquarespeakfittingcalibration,fittheabsorptionspectrumintheregionof710through660cm–1usingaclassicalleastsquaresfit(k-matrixmethod).Thefitmatrixmustincludethederivedspectraoftoluene,1,3-dimethylbenzene,3-ethyltoluene,1,3,5–trimethylbenzene,ethylbenzene,andpropylbenzene(asdeterminedin10.2.6.1).
12.7.3.1Toeliminatespectraloverlaps,subtractthederivedspectraoftoluene,1,3-dimethylbenzene,3-ethyltoluene,1,3,5-trimethylbenzene,ethylbenzeneandpropylbenzene,multipliedbythecoefficientsthatresultedfromtheclassicalleastsquaresfittotheabsorptionspectrum.Inthisway,aresidualbenzenepeakisobtained.
12.7.3.2FittheresidualbenzenepeakwithaLorentzianlineshapefunction(asdefinedin10.2.6.4)withalinearbackgroundintheregionof691through660cm–1anddeterminethepeakheightoftheresidualbenzenepeak.
12.7.3.3Determinethebenzeneconcentrationexpressedinmass%inthefuelsamplebyapplyingthecalibration(see10.2.6)usingthepeakheightoftheresidualbenzenepeakdeterminedin12.7.3.2.
12.7.3.4DeterminethedensityofthefuelsamplebyPrac-ticeD1298orTestMethodD4052.
12.7.3.5Convertthedeterminedmass%tovolume%forthesampleusingtheequationinSection13.
13.Calculation
13.1ConversiontoVolume%ofBenzene—Toconvertthecalibrationandqualificationstandardstovolume%useEq3.
Vb5Mb~Df/0.8844!
(3)
where:
VMb5benzenevolume%,Db5benzenerelativemassdensity%,atand
f515.56°Cofthecalibrationor
qualificationstandardbeingtestedasdeterminedbyPracticeD1298orTestMethodD4052.14.Report
14.1Reportthefollowinginformation:
14.1.1Filterinstruments(TestMethodD6277a).
14.1.1.1Volume%benzenebyTestMethodD6277a,tothenearest0.01%.
14.1.2FTIRinstrumentswithPLScalibration(TestMethodD6277b).
14.1.2.1Volume%benzenebyTestMethodD6277b,tothenearest0.01%.
14.1.3FTIRinstrumentswithCLScalibration(TestMethodD6277c).
14.1.3.1Volume%benzenebyTestMethodD6277c,tothenearest0.1%
15.PrecisionandBias
15.1Interlaboratorytestsofeachoftheprocedures(filter
instruments,FTIRinstrumentswithPLScalibration,andFTIRinstrumentswithCLScalibration)werecarriedoutusingtwentysamplesthatcoveredtherangefrom0to1.8volume%andatleastsixlaboratoriesforeachoftheprocedures.Anadditionalsamplecontainingapproximately4volume%ben-zenewasalsoincludedintheinterlaboratoryresults.Theprecisionofthetestmethodasobtainedbystatisticalexami-nationofinterlaboratoryresults6issummarizedinTable7andTable8andisasfollows:
15.2RepeatabilityforFilterBasedMidIRInstruments—Forbenzeneconcentrationsbetween0.1and1.8volume%,thedifferencebetweensuccessivetestresultsobtainedbythesameoperatorwiththesameapparatusunderconstantoperatingconditionsonidenticaltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceedthefollowingvaluesonlyinonecaseintwenty:
r50.02110.027X
(4)
whereXisthebenzeneconcentrationdetermined.Fortheonesampleatapproximately4volume%benzene,thediffer-encebetweensuccessivetestresults,obtainedbythesameoperatorwiththesameapparatusunderconstantoperatingconditionsonidenticaltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceed0.18onlyinonecaseintwenty.
15.3RepeatabilityforFTIRInstrumentsUsingPLSCali-brationInstruments—Forbenzeneconcentrationsbetween0.1and1.8volume%,thedifferencebetweensuccessivetestresultsobtainedbythesameoperatorwiththesameapparatusunderconstantoperatingconditionsonidenticaltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceedthefollowingvaluesonlyinonecaseintwenty.
r50.0131.052X
(5)
whereXisthebenzeneconcentrationdetermined.Fortheonesampleatapproximately4volume%benzene,thediffer-encebetweensuccessivetestresultsobtainedbythesameoperatorwiththesameapparatusunderconstantoperatingconditionsonidenticaltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceed0.14onlyinonecaseintwenty.
15.4RepeatabilityforFTIRInstrumentsUsingaClassicalLeastSquaresCalibration—Forbenzeneconcentrationsbe-tween0.1and1.8volume%,thedifferencebetweensuccessive
6AvailablefromASTMHeadquarters.RequestRR:D02–1431.
TABLE7RepeatabilitiesasaFunctionofConcentration
BenzeneConcentrationFilterInstruments
FTIRwithPLSFTIRwithCLS(volume%)
Calibration
Calibration
0.10.020.020.050.30.030.030.060.50.030.040.070.70.040.050.080.90.050.060.091.10.050.070.091.30.060.080.101.50.060.090.111.80.070.110.124
0.18
0.14
0.18
TABLE8ReproducibilitesasaFunctionofConcentration
BenzeneConcentration(volume%)
0.10.30.50.70.91.11.31.51.84
FilterInstruments
0.120.120.130.130.130.130.140.14.0.14.0.59
FTIRwithPLSCalibration
0.030.060.080.100.130.150.180.200.230.47
FTIRwithCLSCalibration
0.100.110.110.120.130.130.140.150.150.23
R50.02210.118X(8)
testresultsobtainedbythesameoperatorwiththesameapparatusunderconstantoperatingconditionsonidenticaltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceedthefollowingvaluesonlyinonecaseintwenty.
r50.04710.043X
(6)
whereXisthebenzeneconcentrationdetermined.Fortheonesampleatapproximately4volume%benzene,thediffer-encebetweentwosingleandindependentresultsobtainedbydifferentoperatorsworkingindifferentlaboratoriesonidenti-caltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceed0.47onlyinonecaseintwenty.
15.7ReproducibilityforFTIRInstrumentsUsingaClassi-calLeastSquaresCalibrationInstrument—Forbenzenecon-centrationsbetween0.1to1.8volume%,thedifferencebetweentwosingleandindependentresultsobtainedbydifferentoperatorsworkingindifferentlaboratoriesonidenti-caltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceedthefollowingvaluesonlyinonecaseintwenty.
R50.0991.031X
(9)
whereXisthebenzeneconcentrationdetermined.Fortheonesampleatapproximately4volume%benzene,thediffer-encebetweensuccessivetestresultsobtainedbythesameoperatorwiththesameapparatusunderconstantoperatingconditionsonidenticaltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceed0.18onlyinonecaseintwenty.
15.5ReproducibilityforFilterBasedMidIRInstruments—Forbenzeneconcentrationsbetween0.1and1.8volume%,thedifferencebetweentwosingleandindependentresults,ob-tainedbydifferentoperatorsworkingindifferentlaboratoriesonidenticaltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceedthefollowingvaluesonlyinonecaseintwenty:
R50.1211.012X
(7)
whereXisthebenzeneconcentrationdetermined.Fortheonesampleatapproximately4volume%benzene,thediffer-encebetweentwosingleandindependentresults,obtainedbydifferentoperatorsworkingindifferentlaboratoriesonidenti-caltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceed0.59onlyinonecaseintwenty.
15.6ReproducibilityforFTIRInstrumentsUsingaPLSCalibrationInstrument—Forbenzeneconcentrationsbetween0.1and1.8volume%,thedifferencebetweentwosingleandindependentresultsobtainedbydifferentoperatorsworkingindifferentlaboratoriesonidenticaltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceedthefollowingvaluesonlyinonecaseintwenty:
whereXisthebenzeneconcentrationdetermined.Fortheonesampleatapproximately4volume%benzene,thediffer-encebetweentwosingleandindependentresultsobtainedbydifferentoperatorsworkingindifferentlaboratoriesonidenti-caltestsampleswould,inthelongrun,andinthenormalandcorrectoperationofthetestmethod,exceed0.23onlyinonecaseintwenty.
15.8Bias—Sincetherewerenosuitablereferencematerialsincludedintheinterlaboratorytestprogram,nostatementofbiasisbeingmade.However,thesamplesofthetestprogramweresharedwithaninterlaboratorystudyofTestMethodD5769andsmallbiases(seeNote3)relativetothattestmethodwereobserved.Therelativebiaseswerenotthesameforallprocedures,norweretheythesameforallsampleswithineachprocedure.Becausesuchsamplebiasesarenotcorrectable,userswishingtousethistestmethodtosubstituteforTestMethodD5769,orconversely,arecautionedtoconsiderthespecificsourceorsourcesofsubjectfuelsandtoassure,throughperiodiccomparativetesting,thatanydiffer-encesareconsistentandmanageable.
NOTE3—Theaveragebias,relativetoTestMethodD5769,was-0.06volume%fortheFTIRproceduresand+0.06forthefilterprocedure.Afteraccountingfortheaverages,thefuel-specificdifferencesexceeded0.1volume%foronlyonefuelononeprocedure(outof62combina-tions).
16.Keywords
16.1aromatics;benzene;infraredspectroscopy;spark-ignitionenginefuel
TheAmericanSocietyforTestingandMaterialstakesnopositionrespectingthevalidityofanypatentrightsassertedinconnectionwithanyitemmentionedinthisstandard.Usersofthisstandardareexpresslyadvisedthatdeterminationofthevalidityofanysuchpatentrights,andtheriskofinfringementofsuchrights,areentirelytheirownresponsibility.Thisstandardissubjecttorevisionatanytimebytheresponsibletechnicalcommitteeandmustbereviewedeveryfiveyearsandifnotrevised,eitherreapprovedorwithdrawn.YourcommentsareinvitedeitherforrevisionofthisstandardorforadditionalstandardsandshouldbeaddressedtoASTMHeadquarters.Yourcommentswillreceivecarefulconsiderationatameetingoftheresponsibletechnicalcommittee,whichyoumayattend.IfyoufeelthatyourcommentshavenotreceivedafairhearingyoushouldmakeyourviewsknowntotheASTMCommitteeonStandards,100BarrHarborDrive,WestConshohocken,PA19428.
因篇幅问题不能全部显示，请点此查看更多更全内容