Multistep Method to Extract Moderately Soluble Copper Oxide Nanoparticles from Soil for Quantification and Characterization

Abstract

The objective of this study is to assess how method parameters impact the extraction of moderately soluble CuO nanoparticles (NPs) from a standard natural soil (LUFA 2.1) suitable for chemical analysis. The extraction procedure is comprised of three steps: (i) preconditioning the soil to increase the sodium adsorption ratio, (ii) extracting colloids/NPs from the soil matrix using sonication and a dispersing agent, and (iii) separating the dissolved and nanoparticulate CuO fractions using cloud point extraction. Method parameters of the extraction procedure, including sonication, number of extraction cycles, and dispersing agent, were adjusted to achieve the highest extraction of CuO NPs, while minimizing dissolution. The maximum recovery of CuO NPs ranged from 31% to 42% for an amended concentration range of 10−250 mg-Cu (kg soil)−1 using a preconditioning step to exchange divalent cations for monovalent ions, 0.2% carboxymethyl cellulose (CMC) 700 kg mol–1 as the dispersing agent, probe sonication for 1 min, 3 extraction cycles, and a 1:10 soil-to-liquid ratio. CuO NPs that are polyvinylpyrrolidone (PVP)-coated with a greater stability against aggregation had significantly higher extractability and dissolution. This procedure is the first to effectively extract moderately soluble NPs from soil and experimentally separate them from their dissolved fraction and can be applied to other moderately soluble metal containing natural, incidental, or engineered NPs in soil.

Impacts of Sediment Particle Grain Size and Mercury Speciation on Mercury Bioavailability Potential

“…Three published methods were modified to isolate and size-resolve the nanoparticles from sediments while maximizing the colloidal fraction extracted. ,, The modified method used sonication, dispersing agents (a 0.1 M NaCl solution and an extraction solution containing 2 mM diethylenetriaminepentaacetic acid, 0.1 M triethanolamine, and 0.2 wt % carboxymethyl cellulose), centrifugation, and wet sieving to fractionate the sediments into four size fractions: <0.5 μm (nanophase), 0.5–2 μm (clay), 2–45 μm (silt), and >45 μm (sand). Detailed methods are described in Supporting Information, Text S4 and Schemes S1 and S2.…”

Quantification of anthropogenic TiO2 nanoparticles in soils and sediments combining size fractionation and trace element ratio

“…Overall, the apparent recoveries obtained in this study are comparable to other methods for extracting metal nanoparticles from soils. 12–14,39 The n -TiO 2 concentrations corrected using the apparent recovery were all around 100% of the added concentrations.…”

“…Thus, several studies on extraction methods for nanoparticles from soils have been reported. 12–14 However, the tested nanoparticles were all based on rare elements with low natural backgrounds such as Cu or Ag. On the other hand, trace element ratios have been used to correct for the natural background for various samples containing a high amount of natural particles such as sewage spills, 15 soil, 16 road runoff, 17 surface water, 18 stormwater, 19 and wastewater.…”

Methanol-based extraction protocol for insoluble and moderately water-soluble nanoparticles in plants to enable characterization by single particle ICP-MS

“…Three nanomaterials were dosed to the leaf tissues during testing: Au NP (40-nm gold nanospheres, bare, NanoXact, NanoComposix), CuO NP (copper oxide nanopowder, 10 nm, US Research Nanomaterials, Inc.), and ZnO NP (zinc oxide nanopowder, 80-200 nm, US Research Nanomaterials, Inc.). Notably, the CuO NP diameter was measured by TEM to be 36.6 ± 14.5 nm rather than the manufacturer's listed 10 nm [49]. A 50-nm Au NP (Sigma-Aldrich) was used as a particle standard in ICP-TOF-MS measurement.…”