【astm標(biāo)準(zhǔn)】e 2490 - 09 (2015)

1、Designation:E2490?09(Reapproved2015)StardGuidefMeasurementofParticleSizeDistributionofNanomaterialsinSuspensionbyPhotonCrelationSpectroscopy(PCS)1ThisstardisissuedunderthefixeddesignationE2490thenumberimmediatelyfollowin

2、gthedesignationindicatestheyearofiginaladoptioninthecaseofrevisiontheyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperepsilon()indicatesaneditialchangesincethelastrevisionreapproval.1.Scope1.

3、1Thisguidedealswiththemeasurementofparticlesizedistributionofsuspendedparticleswhicharesolelypredominantlysub100nmusingthephotoncrelation(PCS)technique.Itdoesnotprovideacompletemeasurementmethodologyfanyspecificnanomater

4、ialbutprovidesageneraloverviewguideastothemethodologythatshouldbefollowedfgoodpracticealongwithpotentialpitfalls.1.2Thisstarddoesnotpurpttoaddressallofthesafetyconcernsifanyassociatedwithitsuse.Itistheresponsibilityofthe

5、userofthisstardtoestablishappropriatesafetyhealthpracticesdeterminetheapplicabilityofregulatylimitationspritouse.2.ReferencedDocuments2.1ASTMStards:2E177PracticefUseoftheTermsPrecisionBiasinASTMTestMethodsE691PracticefCo

6、nductinganInterlabatyStudytoDeterminethePrecisionofaTestMethodE1617PracticefReptingParticleSizeacterizationDataF1877PracticefacterizationofParticles2.2ISOStards:ISO133201ParticleSizeAnalysis—LaserDiffractionMethods—Part1

7、:GeneralPrinciples3ISO14488ParticulateMaterials—SamplingSampleSplittingftheDeterminationofParticulateProperties3ISO13321ParticleSizeAnalysis—PhotonCrelationSpectroscopy33.Terminology3.1DefinitionsofTermsSpecifictoThisSta

8、rd:3.1.1Someofthedefinitionsin3.1willdifferslightlyfromthoseusedwithinother(nonparticlesizing)stards(fexamplerepeatabilityreproducibility).FthepurposesofthisGuideonlyweutilizethestateddefinitionsastheyenabletheisolationo

9、fpossibleerrsdifferencesinthemeasurementtobeassignedtoinstrumentaldispersionsamplingvariation.3.1.2crelationcoeff?cientn—measureofthecrelation(similaritycomparison)between2signalsasignalitselfatanotherpointintime.3.1.2.1

10、Discussion—Ifthereisperfectcrelation(thesignalsareidentical)thenthistakesthevalue1.00withnocrelationthenthevalueiszero.3.1.3crelogramcrelationfunctionn—graphicalrepresentationofthecrelationcoefficientovertime.3.1.3.1Disc

11、ussion—Thisistypicallyanexponentialdecay.3.1.4cumulantsanalysisn—mathematicalfittingofthecrelationfunctionasapolynomialexpansionthatproducessomeestimateofthewidthoftheparticlesizedistribution.3.1.5diffusioncoeff?cient(se

12、lfcollective)n—ameasureoftheBrownianmotionmovementofaparticle(s)inamedium.3.1.5.1Discussion—AftermeasurementthevalueisbeinputtedintointheStokesEinsteinequation(Eq1see7.2.1.2(4)).Diffusioncoefficientunitsinphotoncrelation

13、spectroscopy(PCS)measurementsaretypicallym2s.3.1.6Mieregionn—inthisregion(typicallywherethesizeoftheparticleisgreaterthanhalfthewavelengthofincidentlight)thelightscatteringbehaviiscomplexcanonlybeinterpretedwithamerigous

14、exact(allencompassing)they.3.1.6.1Discussion—ThismeexacttheycanbeusedinsteadoftheRayleighRayleighGansDebyeapproximationsdescribedin3.1.83.1.9.Thedifferencesbetweentheapproximationsexacttheyaretypicallysmallinthesizerange

15、consideredbythisstard.Mietheyisneededindertoconvertanintensitydistributiontoonebasedonvolumemass.1ThisguideisunderthejurisdictionofASTMCommitteeE56onNanotechnologyisthedirectresponsibilityofSubcommitteeE56.02onPhysicalCh

16、emicalacterization.CurrenteditionapprovedApril12015.PublishedApril2015.iginallyapprovedin2008.Lastpreviouseditionin2009asE2490–09.DOI:10.1520E249009R15.2FreferencedASTMstardsvisittheASTMwebsitewww.astm.gcontactASTMCustom

17、erServiceat.FAnnualBookofASTMStardsvolumeinfmationrefertothestard’sDocumentSummarypageontheASTMwebsite.3AvailablefromAmericanNationalStardsInstitute(ANSI)25W.43rdSt.4thFloNewYkNY10036:www.ansi.g.Copyright?ASTMInternation

18、al100BarrHarbDrivePOBoxC700WestConshohockenPA194282959.UnitedStates1measuredas60nmin1103MNaClcanhaveahydrodynamicdiameterofover70nmin1106MNaCl(closetodeionizedwater).Indertominimizeanychangesinthesystemondilutionitiscomm

19、ontousewhatiscommonlycalledthe“motherliqu”.Thisistheliquidinwhichtheparticlesexistinstablefmisusuallyobtainedbycentrifugingofthesuspensionmakingupthesameionicnatureofthedispersantliquidifknowledgeofthismaterialisavailabl

20、e.Manybiologicalmaterialsaremeasuredinabuffer(oftenphosphate)whichconfersthecrect(rangeof)conditionsofpHionicstrengthtoassurestabilityofthesystem.Instability(usuallythroughinadequatezetapotential(2)canpromoteagglomeratio

21、nleadingtosettlingsedimentationinasolidliquidsystemcreaminginaliquidliquidsystem(emulsion).Suchfundamentalchangesinterferewiththestabilityofthesuspensionneedtobeminimizedastheyaffectthequality(accuracyrepeatability)ofthe

22、reptedmeasurements.Thesearelikelytobeinvestigatedinanyrobustnessexperiment.7.Procedure7.1Verification:7.1.1Theinstrumenttobeusedinthedeterminationshouldbeverifiedfcrectperfmancewithinpredefinedqualitycontrollimitsbyfollo

23、wingprotocolsissuedbytheinstrumentmanufacturer.TheseconfirmationtestsnmallyinvolvetheuseofonemeNISTtraceableparticlesizestards.Inthesubmicron(1106m)regionthenthesestards(fexampleNISTDukeScientificnowpartofThermoFisherSci

24、entific)tendtobenearlymonodisperse(thatisnarrowsinglemodedistributionPI0.1)whileconfirmingthex(size)axisdonotverifythey(quantityaxis).Furtherthereisalackofavailablestardsfthesub20nmregiontherefebiologicalmaterials(fexamp

25、lebovineserumalbumin–BSAcholesterolhaemsizecontrolleddendrimersAusols)ofknownsize(oftenbymolecularmodeling)canbeutilized.NotethatPCSisafirstprinciplesmeasurementthuscalibrationinthefmalsense(adjustmentoftheinstrumenttore

26、adatrueknownvalue)cannotbeundertaken.Intheeventofa“failure”attheverificationstagethentheissuestocheckinvolvequalityofthedilutionwaterstateofdispersionstabilityofthestardunderdilutionplusinstrumentalissuessuchasthermalsta

27、bilitycleanlinessalignmentofopticalcomponents.Therawcrelogramdatacanbeexaminedduringafteracquisition.Suchexaminationrequiressomeexperiencetraining.Duringdataacquisitiononelooksfstablecountlevelwithoutjumpsleapsinthelevel

28、ofthescatteringcountsthatcouldbeproducedbyparticles(ofdustcontamination)fallingthroughthemeasurementzone(‘numberfluctuations’).Ideallythefmofthecrelogramisanexponentialdecaytoaflatbaseline(approximatingtothephotoncountsi

29、nthesystemwithoutsample)notriseagain(againindicatingnumberfluctuationsinthedata).Manufacturersalsoprovideothermeansofassuringthereliabilityofthedataisrecommendedthattheseprotocolsareconsultedasappropriate.7.1.2Giventhena

30、tureoftheproducedintensitydistributionthelikelihoodthatthesizestardhasbeencertifiedbyelectronmicroscopy(numberdistribution)careneedstobeexercisedindirectcomparisonoftheresults.Facompletelymonodispersesample(everyparticle

31、identical)thenthenumberintensitydistributionsareessentiallyidentical.Ftherealwldsituationwherethereissomepolydispersity(width)tothedistributionthenthenumberdistributionisexpectedtobesmallerthantheproducedintensitydistrib

32、utionthegreaterthepolydispersitythenthelargerthedifferencesbetweenintensityvolumenumberdistributions.Notethatverificationofasystemonlydemonstratesthattheinstrumentisperfmingadequatelywiththeprescribedstardmaterials.Pract

33、icalconsiderationsfrealwldmaterials(especially‘dispersion’ifutilizedifthedistributionisrelativelypolydisperse)meanthatthemethodusedtomeasurethatrealwldmaterialneedstobecarefullyevaluatedfprecision(repeatability).7.2Measu

34、rement:7.2.1Introduction:7.2.1.1Themeasurementofparticlesizedistributioninthenano(sub100nm)regionbylightscatteringdependsontheinteractionoflightwithmattertheromBrownianmotionthatparticleexhibitsinliquidmediuminfreesuspen

35、sion.Theremustbeaninhomogeneityintherefractiveindicesofparticlethemediumwithinwhichitexistsinderflightscatteringtooccur.Withoutsuchaninhomogeneity(fexampleinsocalledindexmatchedsystems)thereisnoscatteringtheparticleisinv

36、isibletolightnomeasurementscanbemadebythePCSanyotherlightscatteringtechnique.7.2.1.2Fparticles100nmasconsideredinthisguideseveralfactsholdtrue:(1)Theamountofscatteringisweakinrelativetermsdependshighlyonthesizeoftheparti

37、cle.IntheRayleighapproximationregion(typicallydλ10inwhichdisthediameterofparticleλisthewavelengthoflightemployed)thenthisintensityofscatteringisproptionaltor6–(volume)2(relativemolecularmass)2.Withacommonlyutilizedhelium

38、neon(HeNe)laser(632.8nm)thenthislimitisapproximately60nm.Thismeansinpracticethata60nmparticlescatters1milliontimesasmuchlightasa6nmparticleofthesamecomposition.Thusitisimperativethatsolutionsarekeptfreeofanycontaminating

39、particlesfexampledustthatareoftenpresentinthelocalenvironmentisusuallyconsiderablylargerthanthematerialthatrequiresmeasurement.Thismeansfilteringliquidsusedtocontaindilutetheparticlestoaleastthesamelevelasthesizeofthepar

40、ticlesthatrequireacterizing.Theveryweakscatteringmeansthatconventionallightdetects(fexamplesiliconphotodiodes)asusedinotherlightscatteringtechnique(fexamplelaserdiffraction)cannotbeused.Thetechniqueofcrelatingthesignalwi

41、thitselfcombinedwithphotoncountingtechniquesisthusemployedtheprinciplebeingthatthenoiseisromwhiletheBrownianmotionisfixed.ConstantlysubtractingthenoisefromtheoverallsignalleavestheretainedBrownianmotionsignal.(2)Theinten