Partitioning and stability of engineered ZnO nanoparticles in soil suspensions using flow field-flow fractionation

Environmental context. Nanoparticulate materials are increasingly being used as catalysts and lubricants, for pollution control and drug delivery, and in electronics, fabrics, cosmetics and sunscreens. In spite of this growth, information about the fate and toxicity of nanoparticles in the environment is limited, partly due to the lack of techniques capable of measuring nanoparticles in complex environmental matrices. One emerging tool, flow field-flow fractionation, can be used to determine the presence and particle size distribution of engineered nanoparticles, for example in soil pore waters, thereby enhancing our understanding of their environmental fate and impacts. Abstract. This paper reports preliminary results for the determination of engineered ZnO nanoparticles using flow field-flow fractionation (FlFFF). This separation technique was used to determine the particle size distributions (PSDs) of ZnO nanoparticles spiked in soil suspensions. Before FlFFF analysis, the soil was prepared in suspension form, shaken overnight and gravitationally settled to extract the <1-µm fraction. The effect of aging was also investigated using soil samples incubated with known concentrations of ZnO nanoparticles for 7 and 14 days. The results show that FlFFF can be used to determine the PSD of engineered nanoparticles and monitor their partitioning and stability in soil suspensions.