The importance of evaluating the real metal concentration in nanoparticles post-synthesis for their applications: A case-study using silver nanoparticles

• Published in: Talanta (Oxford) 2016-01, Vol.146, p.795-800
• Main Authors: Galazzi, Rodrigo Moretto, Santos, Elias de Barros, Caurin, Tatiana, Pessôa, Gustavo de Souza, Mazali, Italo Odone, Arruda, Marco Auréli Zezzio
• Format: Article
• Language: English
• Subjects: Applications; Centrifugation; Characterization; Metal Nanoparticles - chemistry; Microwaves; Nanotechnology; Silver - analysis; Silver - chemistry; Silver determination; Silver nanoparticles
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2015.06.016

To determine whether the effect observed in a study is related to the nanoparticle only or to their synergic effect with the “free” metal ions, the real concentration of silver (104±8 and 100±2mgL−1) after AgNP synthesis is obtained through ICP-MS and ICP OES in the solution after the AgNP synthesis and in different fractions after centrifugation (at 8100g for 40min). From the resuspension of the AgNP contained in the solution (AgNP-total) after synthesis (AgNP-res), concentrations of 49±3 and 51±3mgL−1 are found and concentrations of 50±7 and 47±2mgL−1 in the supernatant (Ag-sup) are found using ICP-MS and ICP OES respectively. The characterization of AgNP-total, AgNP-res and Ag-sup is performed by HRTEM and UV–vis, corroborating the results in terms of Ag determination, and indicates that half of the total silver concentration is in the AgNP form and that the other half is in the “free” silver form. The results of the stability test of the NPs indicate a 7% decrease in Ag as NP three months after its synthesis. [Display omitted] •Silver nanoparticles are used as case-study.•Two fractions are obtained from AgNP synthesis: AgNP-res+Ag-sup.•Silver is determined in all fractions.•Great differences in silver concentrations are found in the fractions.•Only AgNP resuspended is prone to be used in studies with NPs.