Magnetic solid phase extraction of silver-based nanoparticles in aqueous samples: Influence of particle composition and matrix effects on its application to environmental samples and species-selective elution and determination of silver sulphide nanoparticles with sp-ICP-MS

Alexander Urstoeger; Lilly Zacherl; Maximilian Muhr; Yasmin Selic; Monika Wenisch; Marcel Klotz; Michael Schuster

doi:10.1016/j.talanta.2020.122028

Magnetic solid phase extraction of silver-based nanoparticles in aqueous samples: Influence of particle composition and matrix effects on its application to environmental samples and species-selective elution and determination of silver sulphide nanoparticles with sp-ICP-MS

Talanta. 2021 Apr 1:225:122028. doi: 10.1016/j.talanta.2020.122028. Epub 2020 Dec 17.

Authors

Alexander Urstoeger¹, Lilly Zacherl¹, Maximilian Muhr², Yasmin Selic¹, Monika Wenisch¹, Marcel Klotz¹, Michael Schuster³

Affiliations

¹ Division of Analytical Chemistry, Department of Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany.
² Chair of Inorganic and Metal-Organic Chemistry, Department of Chemistry and Catalysis Research Center, Technical University of Munich, Ernst-Otto-Fischer-Straße 1, 85748, Garching, Germany.
³ Division of Analytical Chemistry, Department of Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany. Electronic address: michael.schuster@tum.de.

PMID: 33592757
DOI: 10.1016/j.talanta.2020.122028

Abstract

Silver-based nanoparticles (Ag-b-NPs) are currently a cause for concern because they are being produced in increasing quantities for use in industrial goods and consumer products. This goes hand in hand with their release to the environment and the resultant risks for the entire ecosystem. Therefore, it is essential that these materials are monitored. A promising technique that overcomes a number of shortcomings in handling environmental samples is magnetic solid phase extraction (MSPE) of Ag-b-NPs, which is applied in this study. It has been possible to extract different kinds of Ag-b-NPs at environmentally relevant concentrations in the low ng L^-1 range using iron oxide magnetic particles (IOMPs) of different size and shape with efficiencies in the range from 80 to 100%. Furthermore, environmentally relevant inorganic ions and TiO₂ particles exhibited no major effect on the extraction efficiency. However, natural organic matter (NOM) exhibited a significant influence from 1 mg L^-1 resulting in a 50% drop in extraction efficiency. This effect could be overcome by adding 10 mM Ca²⁺ or increasing the iron oxide magnetic particle (IOMP) concentration to 500 mg L^-1. Applying the presented procedure, Ag-b-NPs added to a river water sample at β_Ag = 50 ng L^-1 were successfully extracted. We also investigated the coextraction of Ag⁺, demonstrating that NOM could eliminate coextraction. The subsequent species-selective elution of Ag₂S-NPs after MSPE, was carried out based on ethylene diamine tetraacetate (EDTA) as eluent in different matrices. A desorption efficiency of 76 ± 6% could be achieved while preserving the Ag₂S-NPs' size. By contrast, core Ag-NPs and AgCl-NPs are dissolved if the presented method is followed.

Keywords: Environmental water samples; Magnetic solid phase extraction; Matrix effect study; Particle size preserving elution; Silver nanoparticles; sp-ICP-MS.