Speciation analysis of silver sulfide nanoparticles in environmental waters by magnetic solid-phase extraction coupled with ICP-MS

Abstract

The growing production and widespread application of silver nanoparticles (AgNPs) have led to their release into the environment, where they are mostly transformed to silver sulfide nanoparticles (Ag 2 S NPs). Thus, speciation analysis of Ag 2 S NPs in environmental matrices is essential for understanding the environmental process and toxic effects of AgNPs. Herein, we report the use of aged iron oxide magnetic particles (IOMPs) as magnetic solid-phase extraction adsorbents for speciation analysis of Ag 2 S NPs. It was found that IOMPs are excellent adsorbents for the selective extraction of silver-containing nanoparticles (AgCNPs) including Ag 2 S NPs, AgNPs and AgCl NPs in the presence of Ag + . More importantly, Ag 2 S NPs can be distinguished from the other AgCNPs by sequential elution. After preeluting AgNPs and AgCl NPs as Ag + with 2% (v/v) acetic acid and IOMPs as the sacrificial oxidants, Ag 2 S NPs were completely eluted as a Ag(I) complex by 10 mM thiourea in 2% (v/v) acetic acid and quantified directly by inductively coupled plasma mass spectrometry (ICP-MS). While the extraction of Ag + was negligible, the maximum extraction of AgCNPs by IOMPs was attained at pH 4.9-6.2, and the interference of humic acid in the AgCNP extraction can be efficiently eliminated by adding Ca 2+ . Under optimized conditions, the method provides low detection limit (0.068 mg L À1 ) and high reproducibility (relative standard deviations < 5.1%) for Ag 2 S NPs. By simultaneously spiking 0.16-10.3 mg L À1 AgNPs and 0.53-14.8 mg L À1 Ag 2 S NPs, the Ag 2 S NP recoveries were in the range of 69.6-100.2% for the tap, river and lake waters; and in the range of 106.2-149.9% for the WWTP effluent due to the part sulfidation of AgNPs to Ag 2 S NPs. Our method is valid for the speciation analysis of Ag 2 S NPs in water samples, which provides an efficient approach for studying the sulfidation of AgNPs and Ag + .

Highly Efficient Removal of Silver-Containing Nanoparticles in Waters by Aged Iron Oxide Magnetic Particles

“…The values of E (4.09–5.17 kJ/mol) indicate that the adsorption of AgCNPs by aged IOMPs is a physisorption process. This agrees well with that obtained in our previous study, where electrostatic interactions between positively charged aged IOMPs and negatively charged AgCNPs at pH 6.2 play key roles in the extraction of AgCNPs …”

“…According to our previous study, aging has little impact on the size and morphology . Here, the size and morphology of the aged IOMPs were investigated with TEM and SEM.…”

“…In our previous work, aged IOMPs (Fe 3 O 4 magnetic particles) were used for speciation analysis of Ag 2 S NPs in environmental waters . The optimum conditions for AgCNP extraction were obtained by investigating the factors, including pH, extraction time, amount of humic acid, the coatings, and sizes of the AgCNPs.…”

Elemental Speciation Analysis in Environmental Studies: Latest Trends and Ecological Impact

“…Overall, the method did not involve the use of harmful solvents or acids, making it a green alternative for analysis [120]. The same authors also developed a MSPE method to quantify Ag 2 S NPs and the remaining fraction of AgNPs in the same samples, by means of a treatment step with acetic acid that dissolved all AgNPs except Ag 2 S NPs [121]. The sample treatment process was devoid of any organic solvent or hazardous substance use, and the preparation of the magnetic sorbent involved only ethylene glycol as solvent, which does not have as high an impact on the environment as other organic compounds.…”

Magnetic Solid Phase Extraction as a Promising Technique for Fast Separation of Metallic Nanoparticles and Their Ionic Species: A Review of Recent Advances

“…The use of aged iron oxide magnetic particles (IOMPs) as MSPE adsorbents for speciation analysis of silver sulfide nanoparticles (Ag 2 SNPs) was described by Zhou et al [ 64 ]. They found that IOMPs are excellent adsorbents for selective extraction of silver-containing nanoparticles (AgCNPs), including Ag 2 SNPs, AgNPs, and AgClNPs in the presence of Ag ions.…”