Identification and characterisation of individual nanoplastics by scanning transmission X-ray microscopy (STXM)

Alexandra Foetisch,Montserrat Filella,Benjamin Watts,Laure-Hélène Vinot,Moritz Bigalke

doi:10.1016/j.jhazmat.2021.127804

Alexandra Foetisch, Montserrat Filella + Show 3 more

Open Access

https://doi.org/10.1016/j.jhazmat.2021.127804

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Abstract

Nanoplastics (NP) are of environmental and human health concern. We tested a novel NP extraction method and scanning transmission X-ray spectro-microscopy (STXM) in combination with near-edge X-ray absorption fine-structure spectroscopy (NEXAFS) to image and identify individual NP in environmental and food matrices. We (1) discussed the potential of STXM compared to other methods potentially suitable for NP analysis, (2) applied the method on NP suspensions of eight of the most common polymers, (3) analyzed environmental water and soil samples spiked with NP and (4) characterized NP in tea water infused in plastic teabags and unspiked soil samples. Here we show that STXM has methodological advantages and that polymers give characteristic spectra, which allows NP identification in environmental and food matrices. For soils we deliver a visual and spectroscopic characterization of NP, proving their presence and highlighting their diversity. Thus, STXM, can be used for the detection and characterisation of NP in different types of matrices.

Highlights

Since 1950, about 8300 million metric tons of plastic have been produced worldwide, 79% of which are accumulated in landfills or in the environment (Geyer et al, 2017)
We (1) discussed the potential of STXM compared to other methods potentially suitable for NP analysis, (2) applied the method on NP suspensions of eight of the most common polymers, (3) analyzed environmental water and soil samples spiked with NP and (4) characterized NP in tea water infused in plastic teabags and unspiked soil samples
Identifying NP in environmental matrices requires the ability to interrogate individual nanoparticles, coupled with a spectroscopic tool with natural contrast that is capable of providing information about molecular structure such that polymers can be distinguished from the natural organic matter that is abundant in all ecosystems

Summary

Introduction

Since 1950, about 8300 million metric tons of plastic have been produced worldwide, 79% of which are accumulated in landfills or in the environment (Geyer et al, 2017). Among the diversity of plastic waste generated, nanoplastics (NP), plastics of a size < 1 μm, are of environmental importance They can be either released directly from manufactured products or produced by the physical, chemical or me chanical degradation of larger polymer objects. Chromatographic analysis of py rolysis products or extracted polymers allow for the identification of polymers but do not provide any information on the size or shape of the particles analysed (Ter Halle et al, 2017; Duemichen et al, 2019). All these characteristics are critical to assess any potential NP environ mental effect. The behavior and fate of NP in the environment have mostly been studied using artificial NP labeled with metals, fluo rescent dyes or enriched stable isotopes (Mitrano et al, 2019; Sander et al, 2019; Li et al, 2020)

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