A.A. Galyean, W.N. Vreeland, J.J. Filliben, R.D. Holbrook, H.S. Weinberg
University of North Carolina at Chapel Hill, US
nanomaterials, asymmetric flow field flow fractionation, AF4, separation, complex matrix, polydispersity, quasi-elastic light scattering, QELS, differential number fraction
The development of standardized and optimized methods to monitor the behavior of engineered nanomaterials (ENMs) in complex environments is considered a critical component in ENM risk assessment. Robust, rigorously optimized methods are currently lacking, in part because of matrix variability, sample polydispersity, and a lack of understanding how primary instrument factors affect method performance. To this end, a practical and effective separation method has been explored that optimizes asymmetric flow field flow fractionation (AF4) separation protocols with an online quasi-elastic light scattering (QELS) detector. An assessment metric to better interpret particle sizing data following separation of complex nanomaterial samples was identified using a hydrodynamic radius differential that determines relative separation protocol success. Using this metric, the AF4 separation of a complex sample can be optimized. Full optimization is realized when a higher retention separation does not produce a smaller measured radius differential that is larger than the associated uncertainty.