@ Marwah, you can use either AAS or ICP-MS.

I think this article will be helpful

Ashraf, J., Ansari, M., Khan, H. et al. Green synthesis of silver nanoparticles and characterization of their inhibitory effects on AGEs formation using biophysical techniques. Sci Rep 6, 20414 (2016). https://doi.org/10.1038/srep20414

Hello Marwah,

many thanks for sharing this important technical question which will certainly be of broad interest to other RG members as well. The green synthesis and characterization of silver nanoparticles continues to be a hot research topic. In this context please have a look e.g. at the following potentially useful articles which could help answering your question:

Rapid method to estimate the concentration of citrate capped silver nanoparticles from UV-visible light spectra

Article Rapid method to estimate the concentration of citrate capped...

and

Size-controlled silver nanoparticles synthesized over the range 5–100 nm using the same protocol and their antibacterial efficacy

Article Size-controlled silver nanoparticles synthesized over the ra...

Fortunately both articles are freely available as public full texts on RG. Moreover, there is a vast body of relevant literature on silver nanoparticles available in the literature. To find and access other helpful articles you can use the "Search" function of RG. Just search for "silver nanoparticles" and then click on "Publications":

https://www.researchgate.net/search.Search.html?type=publication&query=silver%20nanoparticles

This will provide you with a long list of potentially useful papers on this topic, many of them even posted as public full texts.

Good luck with your research work and best wishes, Frank Edelmann