A Novel Strategy for the Detection and Quantification of Nanoplastics by Single Particle Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

Abstract

A method for the detection and quantification of nanoplastics (NPTs) at environmentally relevant concentrations was developed. It is based on conjugating nanoplastics with functionalized metal (Au)-containing nanoparticles (NPs), thus making them detectable by highly sensitive inductively coupled plasma mass spectrometry (ICP-MS) operated in single particle (SP) mode. The selectivity of the method was achieved by the coupling of negatively charged carboxylate groups present at the surface of nanoplastics with a positively charged gelatin attached to the custom-synthesized AuNPs. The adsorbed Au produced a SP-ICP-MS signal allowing the counting of individual nanoplastic particles, and hence their accurate quantification (< 5% error). Polystyrene (PS) particle models with controlled surface functionalization mimicking the nanoplastics formed during natural degradation of plastic debris were used for the method development. The nanoplastic number concentration quantification limit was calculated at 8.4 x 10 5 NPTs L-1 and the calibration graph was linear up to 3.5 x 10 8 NPTs L-1. The method was applied to the analysis of nanoplastics of up to 1 µm in drinking, tap and river water. The minimum detectable and quantifiable size depended on the degree of functionalization and the surface available for labeling. For a fully functionalized nanoplastic, the lower size detectable by this strategy is reported as 135 nm. In this study, authors use the recommendation for the definition of nanoplastics as plastic particles with sizes ranging between 1 nm and 1 µm, although it has not been accepted by a dedicated organization.

Nanoplastic Labelling with Metal Probes: Analytical Strategies for Their Sensitive Detection and Quantification by ICP Mass Spectrometry

“…The synthesis and characteristics of soap-free polystyrene model materials were detailed elsewhere [ 42 ]. The synthesis of gelatin coated AuNPS (AuNPS@gel) was described elsewhere [ 40 ]. Ultrapure water (18 MΩ cm −1 ) obtained with a MilliQsystem (Millipore, Guyancourt, France) was used throughout.…”

“…In a previous work, the applicability of the labelling of NPTs using gold nanoparticles by means of SP-ICP-MS was demonstrated by our research group [ 40 ]. The analytical method developed showed an accurate quantification (<5% error) for high functionalized NPTs up to 1 µm.…”

Challenges in characterization of nanoplastics in the environment

“…All of the above mass spectrometry methods have limited capabilities of quantification. By contrast, single particle-inductively coupled plasma mass spectroscopy (ICP-MS) achieved a detection limit of 8.4 Â 10 8 nanoparticles per liter for polystyrene (PS) particle with plastic particles size ranging from 1 nm and 1 µm (Jiménez-Lamana et al, 2020).…”

Amino-Functionalized Polystyrene Nano-Plastics Induce Mitochondria Damage in Human Umbilical Vein Endothelial Cells

“…The increasing accumulation of plastic wastes in the environment has become a major cause for concern because of their adverse effects on the ecosystem and human health [ 1 , 2 , 3 ]. UV-exposure, and external and biological degradation were reported to be responsible for the breakdown of plastics into micro-particles <5000 nm in diameter, and further into nanoparticles (NPs) <100 nm in diameter [ 4 , 5 ]. As emerging contaminants, nano-plastics refer to plastic particles with sizes ranging between 1 nm and 1 μm [ 6 ].…”