Improvements in Nanoparticle Tracking Analysis To Measure Particle Aggregation and Mass Distribution: A Case Study on Engineered Nanomaterial Stability in Incineration Landfill Leachates

Abstract

Numerous nanometrology techniques have been developed in recent years to determine the size, concentration, and a number of other characteristics of engineered nanomaterials (ENM) in environmental matrices. Among the many available techniques, nanoparticle tracking analysis (NTA) can measure individual particles to create a size distribution and measure the particle number. Therefore, we explore the possibility to use these data to calculate the particle mass distribution. Additionally, we further developed the NTA methodology to explore its suitability for analysis of ENM in complex matrices by measuring ENM agglomeration and sedimentation in municipal solid waste incineration landfill leachates over time. 100 nm Au ENM were spiked into DI HO and synthetic and natural leachates. We present the possibility of measuring ENM in the presence of natural particles based on differences in particle refractivity indices, delineate the necessity of creating a calibration curve to adjust the given NTA particle number concentration, and determine the instruments linear range under different conditions. By measuring the particle size and the particle number distribution, we were able to calculate the ENM mass remaining in suspension. By combining these metrics together with transmission electron microscopy (TEM) analyses, we could assess the extent of both homo- and heteroagglomeration as well as particle sedimentation. Reporting both size and mass based metrics is common in atmospheric particle measurements, but now, the NTA can give us the possibility of applying the same approach also to aqueous samples.

A review of the fate of engineered nanomaterials in municipal solid waste streams

“…In-depth investigations on field-scale landfills have confirmed the abundance of nanoparticulate fractions in leachates (Hennebert et al 2013;Jensen and Christensen 1999;Kaegi et al 2017;Matura et al 2012;Mehrabi et al 2017;Mitrano et al 2017), although it should be noted that the origin of these nanoemissions may be from natural sources or from ENMs. Alteration and weathering processes could cause unwanted ENM release that may consequently pose a threat towards groundwater contamination and may lead to unknown adverse impacts on the environment.…”

Detection of nanoparticles in edible plant tissues exposed to nano-copper using single-particle ICP-MS

“…Thus, these approaches cannot be used for more realistic samples (e.g., multimodal size, other non-target NPs). The nanoparticle tracking analysis system (Gallego-Urrea et al 2011;Mehrabi et al 2017;Mitrano et al 2017; Shang and Gao 2014) offers some improvements, since it can track particles with more complex particle-size distributions, but also requires concentrations in the ppm range, provides no information on composition, and would be challenging to use with more realistic samples containing natural and incidental NPs. These approaches will continue to be extremely useful for understanding the fundamental behavior of NPs in different media, but there is a need to be aware of the limitations.…”

Strategies for determining heteroaggregation attachment efficiencies of engineered nanoparticles in aquatic environments

“…63 Additionally, the detection threshold can be adjusted so that only particles with high scattering intensity are measured. 75 A fluorescence optical filter can be used for measuring fluorescence in parallel to scattering intensity, and using the extended dynamic range mode two parallel videos can be analyzed with different optical settings. 70 The simultaneous measurement of particle trajectories with scattering intensity and/or fluorescence could be utilized for determining heteroaggregation rates between particles with different scattering intensities and/or fluorescence properties.…”