Asymmetric Flow Field-Flow Fractionation of Manufactured Silver Nanoparticles in Soil Water Extracts

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Manufactured silver nanoparticles (AgNP) are among the most widely used nanoparticles in consumer products and their unintended release into the environment has become a serious concern. For a meaningful assessment of the risks of AgNP in soils, their concentration and particle-size-distribution in soil pore water need to be measured. This can be done by using asymmetric flow field-flow fractionation (AF4), which is an analytical technique for the continuous fractionation of nanoparticles as a function of their diffusion coefficient. AF4 can be combined with UV-Vis or HR-ICP-MS spectroscopy to detect and quantify AgNP of different sizes. So far, the selection of a mobile AF4 phase to characterize AgNP in soil pore water has received very little attention. Hence, the focus of our study was to select a mobile AF4 phase required to successfully separate and quantify AgNP in soil water extracts. The AgNP varied between 10 and 90 nm in size and were either capped with citrate or polyvinylpyrrolidone (PVP). Soils with contrasting properties were selected to generate water extracts varying in pH and in concentrations of dissolved organic matter and clay colloids. During AF4 analysis, AgNP were detected using a combination of on-line UV-Vis and off-line HR-ICP-MS measurements. The choice of the mobile AF4 phase strongly affected the recovery of AgNP in soil water extracts during fractionation. With UPW as a mobile phase, citrate- and PVP-coated AgNP of different sizes were almost entirely recovered within the void peak. In contrast, a good separation and recovery of these AgNP was obtained when SDS was used. The presence of clay colloids in the soil water extracts dramatically increased the elution time of PVP-coated AgNP, suggesting an interaction between these AgNP and clay minerals. The use of SDS as a mobile AF4 phase holds promise to successfully characterize AgNP in soil pore water.
Original languageEnglish
Publication statusPublished - 2013
EventMicroNanoConference 2013 -
Duration: 11 Dec 201312 Dec 2013


ConferenceMicroNanoConference 2013


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