Silver nanoparticles (AgNPs) were detected and characterized in several silver colloidal products available on the market. The relationship of the diameter of the nanoparticle with the corresponding peak potential was used to determine the dimensions of AgNPs in real samples. Quantitative analysis was carried out by voltammetry of immobilized particles on screen printed and glassy carbon electrodes. Screen printed electrodes were used prior to modification of the reference electrode to attain stable readings of peak potential. The repeatability of the modification as well as the quantitative results was checked and found satisfactory

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Chemical composition, size and structure of the nanoparticle are required to describe nanoceria. Nanoparticles of similar size and Ce(III) content might exhibit different chemical behaviour due to their differences in structure. A simple and direct procedure based on affordable techniques for all the laboratories is presented in this paper. The combination of Raman and UV-vis spectroscopy and particle impact coulometry (PIC) allows the characterization of nanoceria of small size from 4 to 65 nm at a concentration from micromolar to nanomolar, a concentration range suitable for the analysis of lab-prepared or commercial nanoparticle suspensions, but too high for most analytical purposes aimed at nanoparticle monitoring. While the PIC limits of size detection are too high to observe small nanoparticles unless catalytic amplification is used, the method provides a simple means to study aggregation of nanoparticles in the media they are needed to be dispersed for each application. Raman spectroscopy provided information about structure of the nanoparticle, and UV-vis about their chemical behaviour against some common reducing and oxidizing agents. Graphical Abstract To characterize nanoceria it is necessary to provide information about the shape, size and structure of the nanoparticles as well as the chemical composition.

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