Extraction Method Development for Quantitative Detection of Silver Nanoparticles in Environmental Soils and Sediments...

For understanding the environmental behavior and toxicity of Ag nanoparticles (Ag-NPs), a quantitative method for characterizing the AgNPs in soils and sediments is urgently needed. In this study, we validated a previously developed extraction method by optimizing the extraction of silver nanoparticles from soil and sediment samples to which engineered AgNPs had been added. The samples were analyzed by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). Initially, different extraction conditions were evaluated to validate the optimal extraction procedure. Then the optimal extraction procedure was applied to environmental soil and sediment samples spiked with AgNPs. The extraction data for Ag-NPs with sizes below 30 nm was not shown due to the particle size detection limit of the SP-ICP-MS method (∼20 nm). The number concentrations of Ag particles extracted from different environmental soils and sediments matrices were in the range of (12 ± 1-23 ± 1) × 10⁷ particles/g soil. Similarly, 53.4-100.0% of the particulate Ag mass was recovered. For the relatively low Ag mass recovery of Guiyu agricultural soil, the Ag mass recovery shows great improvement (from 53.4 to 105.8%) by the soil dilution using SiO₂. The optimal method was validated to be feasible for extracting Ag-NPs from environmental soils and sediments, except for the soil with high soil organic matter (SOM) content. The SiO₂ dilution of soil provides a promising way to promote the extraction of Ag-NPs in soil (or sediment) with high SOM content, which could further promote the study on the environmental behavior and toxicity of Ag-NPs in soil and sediment environment.