title: Particle size distributions by transmission electron microscopy: an interlaboratory comparison case study.
abstract: This paper reports an interlaboratory comparison that evaluated a protocol for measuring and analysing the particle size distribution of discrete, metallic, spheroidal nanoparticles using transmission electron microscopy (TEM). The study was focused on automated image capture and automated particle analysis. NIST RM8012 gold nanoparticles (30 nm nominal diameter) were measured for area-equivalent diameter distributions by eight laboratories. Statistical analysis was used to (1) assess the data quality without using size distribution reference models, (2) determine reference model parameters for different size distribution reference models and non-linear regression fitting methods and (3) assess the measurement uncertainty of a size distribution parameter by using its coefficient of variation. The interlaboratory area-equivalent diameter mean, 27.6 nm ± 2.4 nm (computed based on a normal distribution), was quite similar to the area-equivalent diameter, 27.6 nm, assigned to NIST RM8012. The lognormal reference model was the preferred choice for these particle size distributions as, for all laboratories, its parameters had lower relative standard errors (RSEs) than the other size distribution reference models tested (normal, Weibull and Rosin-Rammler-Bennett). The RSEs for the fitted standard deviations were two orders of magnitude higher than those for the fitted means, suggesting that most of the parameter estimate errors were associated with estimating the breadth of the distributions. The coefficients of variation for the interlaboratory statistics also confirmed the lognormal reference model as the preferred choice. From quasi-linear plots, the typical range for good fits between the model and cumulative number-based distributions was 1.9 fitted standard deviations less than the mean to 2.3 fitted standard deviations above the mean. Automated image capture, automated particle analysis and statistical evaluation of the data and fitting coefficients provide a framework for assessing nanoparticle size distributions using TEM for image acquisition.
authors.affiliation: Lawrence Murphy, Cabot Corporation, 157 Concord Road, Billerica, MA 01821, USA.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Rice
authors.affiliation: Dupont Central Research and Development, Experimental Station-Bldg 228, PO Box 80228, Wilmington, DE 19880-0228, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Chan
authors.affiliation: Dupont Central Research and Development, Experimental Station-Bldg 228, PO Box 80228, Wilmington, DE 19880-0228, USA.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Brown
authors.affiliation: Hewlett Packard Corporation, OR, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Eschbach
authors.affiliation: RTI International, Aerosol Science, Nanotechnology Engineering Technology Unit, 3040 Cornwallis Rd, PO Box 12194, Research Triangle Park, NC 27709, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Han
authors.affiliation: RTI International, Aerosol Science, Nanotechnology Engineering Technology Unit, 3040 Cornwallis Rd, PO Box 12194, Research Triangle Park, NC 27709, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Ensor
authors.affiliation: National Institute for Occupational Safety and Health, 095 Willowdale Road, Morgantown, WV 26505, USA.
authors.forename: Aleksandr B
authors.initials: AB
authors.lastname: Stefaniak
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Drive, Stop 8443, Gaithersburg, MD 20899-8443, USA.
authors.forename: John
authors.initials: J
authors.lastname: Bonevich
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Drive, Stop 8443, Gaithersburg, MD 20899-8443, USA.
authors.forename: András E
authors.initials: AE
authors.lastname: Vladár
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Drive, Stop 8443, Gaithersburg, MD 20899-8443, USA.
authors.forename: Angela R
authors.initials: AR
authors.lastname: Hight Walker
authors.affiliation: US Food and Drug Administration, Division of Chemistry and Materials Science (DCMS), WO62, Room G102, 10903 New Hampshire Avenue, Silver Spring, MD 20993, USA.
authors.forename: Jiwen
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Statistics Department and Applied Statistics Laboratory, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Starnes
authors.affiliation: Statistics Department and Applied Statistics Laboratory, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: Arnold
authors.initials: A
authors.lastname: Stromberg
authors.affiliation: Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: Jia
authors.initials: J
authors.lastname: Ye
authors.affiliation: Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Grulke