Evaluation of Nanoparticle Tracking Analysis (NTA) for the Measurement of Nanoplastics in Drinking Water

Abstract

In the last few years, microplastics have been detected in fresh- and seawater, atmosphere, sediments, soils, sewage sludge, biota and food. However, these microplastics can degrade to even smaller plastic particles in the sub-micron range, the nanoplastics. Only a few studies so far confirmed the presence of NP in environmental samples and their release during the use of personal care products, the boiling of plastic teabags and the use of plastic infant bottles. Due to their smaller dimensions and colloidal properties, nanoplastics could pose an increased hazard to the environment, biota and humans. While there are methods for detecting microplastics, the reliable detection and quantification of size and particle number concentrations of plastic particles less than a micrometre in size are still difficult. In this study, the performance characteristics of nanoparticle tracking analysis (NTA) for detecting nanoplastics using an NS300 instrument were determined after optimisation. The NS300 proved to be accurate and precise for a 102 nm Nanospheres suspension, showing favourable results for accuracy, repeatability and reproducibility at high and low particle number concentrations. While the concentration range was linear from 5.0x106 to 2.0x109 particles/mL, the particle size range of the NS300 instrument was linear from 46 to >350 nm. From the measurements of mixtures of particles, it is clear that NTA has difficulties with polydisperse mixtures resulting in an underestimation of the smaller particle sizes. Finally, eight brands of bottled mineral water were analysed. The particle number concentrations ranged from 1.0x106 to 2.2x107 particles/mL, with mean particle sizes in the range of 110 to 170 nm and mode particle sizes <100 nm for all samples. Particle size distributions showed a particle size range of 50 to 500 nm.

Micro and nanoplastics pollution: A review on global concern and its impacts on ecosystems

“…Detection and analytical techniques for identifying and quantifying MNPs are essential tools for understanding the extent of plastic pollution and its impact on the environment (Fu et al, 2020). Various methods have been developed to detect and characterize these tiny plastic particles in environmental samples such as visual inspection (Burns & Boxall, 2018), spectroscopic technique (Renner et al, 2017; Ribeiro‐Claro et al, 2017), scanning electron microscopy (SEM) (Wang et al, 2017), pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) (Käppler et al, 2018), micro‐Fourier transform infrared spectroscopy (Micro‐FTIR) (Käppler et al, 2016), flow cytometry (Bianco et al, 2023), and NTA (Peters et al, 2022). In visual inspection, MPs can be observed using optical microscopy, where particles are manually counted and categorized based on shape, size, and color.…”

“…Flow cytometry is a high-throughput method for the quantification of MPs in environmental samples based on their fluorescence properties (Kaile et al, 2020). NTA is used to detect and measure nanoparticles, including NPs, by tracking their Brownian motion in a suspension (Peters et al, 2022). Each detection and analytical technique has its advantages and limitations, and combining multiple methods can provide more comprehensive information about the presence and characteristics of MNPs in environmental samples.…”

Micro(nano)plastics: invisible compounds with a visible impact

“…The quantitation and analysis of MNPs are essential for accurately assessing their existence and intensity in different environmental samples. 11 A number of techniques are employed for quantification depending on the type of MNPs sample and the size range of MNPs being investigated such as density separation and filtration, 12 microscopic and spectroscopic techniques, 11 chromatographic approach, 13 nanoparticle tracking analysis (NTA), 14 quantitative polymerase-chain-reaction (qPCR) approach 15 ( Figure 3 ).…”

“…In addition, nanoparticle tracking analysis (NTA) has also been considered an optical technique for tracking individual MNP particles based on their Brownian motion. 14 It provides information on particle size distribution and concentration as well. More recently, quantitative polymerase chain reaction (qPCR), a technique within molecular biology based on MNP ingested by microorganisms or organisms, has also been practised.…”

Capillary Electrophoresis as a Complementary Analytical Tool for the Separation and Detection of Nanoplastic Particles

“…In view of the proposed background, it has been hypothesized that CE coupled with an appropriate detection device may be a fit-for-purpose analytical technique to identify and quantify nanoplastics. , This technique is called for providing deeper insights into size distribution and surface charge functionality of the aforementioned particles in the matrix subject to study. Therefore, CE in combination with a ultraviolet–visible (UV–vis) spectrophotometric diode-array detector (DAD) has been evaluated for the nanometrological approach herein described in which separation of various types of nanoplastic particles with different diameters has been dealt with, together with a study of electrophoretic parameters calculated from both experimental measurements on CE and laser Doppler velocimetry (LDV) as a supplementary technique.…”