TiO2 engineered nanoparticles (ENPs) are widely used in paints, photocatalysts, food, cosmetics, etc. The large scale of TiO2 production and application leads to their inevitable release into the environment, which raises concern regarding their environmental and human health risks. To achieve better risk assessment, it is critical to measure the concentrations of engineered nanoparticle in the environment. The main obstacles of detecting and quantifying ENPs in the environment are 1) the low expected environmental concentrations of engineered nanoparticles, 2) the abundance of homologous natural nanoparticles, and 3) heteroaggregation of natural and engineered nanoparticles in environmental samples. This presentation will discuss a novel approach for extraction and quantification of TiO2 ENPs in natural soils. This approach is based on 1) extraction of nanoparticles using 10 mM Sodium Pyrophosphate to break down nanoparticle heteroaggregates and release nanoparticles as primary particles or smalle aggregates, and 2) differentiating ENPs from NNPs based on shifts in elemental ratios (e.g., Ti/Nb), where Ti/Nb ratios are greater than the average crustal Ti/Nb ratio indicate the occurrence of anthropogenic TiO2 in a given sample. The elemental ratios were calculated for different extracted size fractions (ca., &lt;100 nm, &lt;450 nm and &lt;1000 nm). Ti/Nb ratios increased following the order Ti/Nb100nm &lt; Ti/Nb1000nm &lt; Ti/Nb450nm, indicating that TiO2 particles occur as either large primary particles (ca. TiO2 pigments) or aggregates of ENPs. Size-based elemental composition of the extracted nanoparticles (obtained by field flow fractionation coupled to inductively coupled plasma mass spectrometer (FFF-ICP-MS)) indicate that the majority of TiO2 occur within the size range 100-200 nm. The presented approach can be implemented widely for the detection and quantification of ENPs in environmental systems.

Quantification of TiO2 engineered nanoparticles in natural soils

2019 Spring National Meeting

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