Influence of Particle Coating and Matrix Constituents
on the Cloud Point Extraction Efficiency of Silver Nanoparticles (Ag-NPs)
and Application for Monitoring the Formation of Ag-NPs from Ag<sup>+</sup>
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Abstract
For the quantification of silver
nanoparticles (Ag-NPs) in environmental
samples using cloud point extraction (CPE) for selective enrichment,
surface modification of the Ag-NPs and matrix effects can play a key
role. In this work we validate CPE with respect to the influence of
different coatings and naturally occurring matrix components. The
Ag-NPs tested were functionalized with inorganic and organic compounds
as well as with biomolecules. Commercially available NPs and NPs synthesized
according to methods published in the literature were used. We found
that CPE can extract almost all Ag-NPs tested with very good efficiencies
(82β105%). Only Ag-NPs functionalized with BSA (bovine serum
albumin), which is a protein with the function to keep colloids in
solution, cannot be extracted. No or little effect of environmentally
relevant salts, organic matter, and inorganic colloids on the CPE
of AgNPs was found. Additionally we used CPE to observe the <i>in situ</i> formation of Ag-NPs produced by the reduction of
Ag<sup>+</sup> with natural organic matter (NOM)