ASTM_E_2490_-_09_2015.pdf

Designation:E249009(Reapproved 2015)Standard Guide forMeasurement of Particle Size Distribution of Nanomaterialsin Suspension by Photon Correlation Spectroscopy(PCS)1This standard is issued under the fixed designation E2490;the number immediately following the designation indicates the year oforiginal adoption or,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.Scope1.1 This guide deals with the measurement of particle sizedistribution of suspended particles,which are solely or pre-dominantly sub-100 nm,using the photon correlation(PCS)technique.It does not provide a complete measurement meth-odology for any specific nanomaterial,but provides a generaloverview and guide as to the methodology that should befollowed for good practice,along with potential pitfalls.1.2 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility 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:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1617 Practice for Reporting Particle Size CharacterizationDataF1877 Practice for Characterization of Particles2.2 ISO Standards:ISO 13320-1 Particle Size AnalysisLaser DiffractionMethodsPart 1:General Principles3ISO 14488 Particulate MaterialsSampling and SampleSplitting for the Determination of Particulate Properties3ISO 13321 Particle Size AnalysisPhoton CorrelationSpectroscopy33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 Some of the definitions in 3.1 will differ slightly fromthose used within other(non-particle sizing)standards(forexample,repeatability,reproducibility).For the purposes ofthis Guide only,we utilize the stated definitions,as they enablethe isolation of possible errors or differences in the measure-ment to be assigned to instrumental,dispersion or samplingvariation.3.1.2 correlation coeffcient,nmeasure of the correlation(or similarity/comparison)between 2 signals or a signal anditself at another point in time.3.1.2.1 DiscussionIf there is perfect correlation(the sig-nals are identical),then this takes the value 1.00;with nocorrelation then the value is zero.3.1.3 correlogram or correlation function,ngraphical rep-resentation of the correlation coefficient over time.3.1.3.1 DiscussionThis is typically an exponential decay.3.1.4 cumulants analysis,nmathematical fitting of thecorrelation function as a polynomial expansion that producessome estimate of the width of the particle size distribution.3.1.5 diffusion coeffcient(self or collective),na measureof the Brownian motion movement of a particle(s)in amedium.3.1.5.1 DiscussionAfter measurement,the value is beinputted into in the Stokes-Einstein equation(Eq 1,see7.2.1.2(4).Diffusion coefficient units in photon correlationspectroscopy(PCS)measurements are typically m2/s.3.1.6 Mie region,nin this region(typically where the sizeof the particle is greater than half the wavelength of incidentlight),the light scattering behavior is complex and can only beinterpreted with a more rigorous and exact(and all-encompassing)theory.3.1.6.1 DiscussionThis more exact theory can be usedinstead of the Rayleigh and Rayleigh-Gans-Debye approxima-tions described in 3.1.8 and 3.1.9.The differences between theapproximations and exact theory are typically small in the sizerange considered by this standard.Mie theory is needed inorder to convert an intensity distribution to one based onvolume or mass.1This guide is under the jurisdiction of ASTM Committee E56 on Nanotech-nology and is the direct responsibility of Subcommittee E56.02 on Physical andChemical Characterization.Current edition approved April 1,2015.Published April 2015.Originallyapproved in 2008.Last previous edition in 2009 as E2490 09.DOI:10.1520/E2490-09R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.7 polydispersity index(PI),ndescriptor of the width ofthe particle size distribution obtained from the second and thirdcumulants(see 8.3).3.1.8 Rayleigh-Gans-Debye region,nin this region(statedto be where the diameter of the particle is up to half thewavelength of incident light),the scattering tends to theforward direction,and again,an approximation can be used todescribe