title: Characterization of polymeric nanomaterials using analytical ultracentrifugation.
abstract: The characterization of nanomaterials represents a complex analytical challenge due to their dynamic nature (small size, high reactivity, and instability) and the low concentrations in the environment, often below typical analytical detection limits. Analytical ultracentrifugation (AUC) is especially useful for the characterization of small nanoparticles (1-10 nm), which are often the most problematic for the commonly used techniques such as electron microscopy or dynamic light scattering. In this study, small polymeric nanomaterials (allospheres) that are used commercially to facilitate the distribution of pesticides in agricultural fields were characterized under a number of environmentally relevant conditions. Under most of the studied conditions, the allospheres were shown to have a constant hydrodynamic diameter (dH) of about 7.0 nm. Only small increases in diameter were observed, either at low pH or very high ionic strength or hardness, demonstrating their high physicochemical stability (and thus high mobility in soils). Furthermore, natural organic matter had little effect on the hydrodynamic diameters of the allospheres. The concentration of the nanoparticles was an important parameter influencing their agglomeration-results obtained using dynamic light scattering at high particle concentrations showed large agglomerate sizes and significant particle losses through sedimentation, clearly indicating the importance of characterizing the nanomaterials under environmentally relevant conditions.
authors.affiliation: Department of Chemistry, Biophysical Environmental Chemistry Group, University of Montreal, C.P. 6128, Succursale Centre-ville, Montreal, Quebec, Canada H3C 3J7.
authors.forename: Leosveys
authors.initials: L
authors.lastname: Diaz
authors.affiliation: Department of Chemistry, Biophysical Environmental Chemistry Group, University of Montreal, C.P. 6128, Succursale Centre-ville, Montreal, Quebec, Canada H3C 3J7.
authors.forename: Caroline
authors.initials: C
authors.lastname: Peyrot
authors.affiliation: Department of Chemistry, Biophysical Environmental Chemistry Group, University of Montreal, C.P. 6128, Succursale Centre-ville, Montreal, Quebec, Canada H3C 3J7.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Wilkinson
mesh_terms: D002118:Calcium / Q000032:analysis; D004586:Electrophoresis; D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis; D009994:Osmolar Concentration; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D014461:Ultracentrifugation / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D009930:Organic Chemicals; D011108:Polymers; D014874:Water Pollutants, Chemical; D002118:Calcium