Comparison of the effects of different protocols on the particle size distribution of TiO2 dispersions

Abstract

tThere is a need to standardize methods associated with the dispersion of nanomaterials innano(eco)toxicological investigations. The first step toward this goal is to understand the degree of vari-ability that exists in nanomaterial dispersions prepared by using different protocols. Using two casestudies, the degree of variability in TiO2nanomaterial dispersions was assessed by differential centrifugalsedimentation (DCS) methods. Case study 1 addresses the variability that arises from variations within oneprotocol, investigating the effects of dispersion aging, sonication exposure time, sonication in the pres-ence/absence of an ice bath, material subsampling, particle concentration and having a pre-wetting step.Case study 2 addresses the variability between four different protocols developed through past researchactivities and projects. The results indicate that there is a large degree of variability (relative standarddeviation (RSD) of mean particle diameter = 26%) in the dispersion of TiO2nanomaterials between the fourdifferent protocols studied and that several steps in a dispersion protocol are potential sources of vari-ation, with final particle concentration being the most significant. The implication of this study is clear:for the purpose of data comparability, there is a need to provide the exact details of all steps involved ina dispersion protocol.© 2014 Published by Elsevier