Hello. I had synthesized silver nanoparticles using mangrove plant extraction. And I need to know the concentration for further test. How can I calculate/determine the concentration of silver nanoparticle solution that had been produced? Can we determine the concentration from the abs value of UV-Vis spectro?
Thank you.
You can measure the Ag+ ions in a solution before and after the reduction.
Dear Alia,
You may be able to determine your Ag NP using UV-vis absorption technique, but you needa stabdard or control of known Ag NP concentration. If you do this for the first time, I suggest to check the weight of your Ag NP in powder or you can also check the atomic density of your samples by EDS/EDAX analysis.
good luck.
To determine AgNP content by UV-vis you need to prepare the standards: a wide concentration range of AgNP dispersions with the particles of same shape and size dispersed in the plant extract. But it is difficult approach. The better pathway is a separation of AgNP from reactive media by centrifugation followed by its dissolution in weak HNO3 and analysis by UV-vis (see http://onlinelibrary.wiley.com/doi/10.1002/hlca.19490320204). The method is quite old but allows to analyze the silver at ultralow content.
UV-visible spectroscopy is one of the popular characterization techniques to determine particle formation and its properties. It well known that UV-Vis peak of Ag NPs is in the range of about ~385-470 nm which depended to size, shape , distribution and agglomeration. It is necessary to remove impurities from your sample before recording the UV-vis ,clear absorption from the Ag NPs depends on homogeneously and purity . To remove impurities ,you must to centrifuge Ag NPs solution and o collect only Ag NPs. Repeat this process several times by dispersion Ag NPs in water .Then you can measure the Ag NPs UV-Vis absorption. You must to prepare and graph standard or calibration curve between absorbance of Ag NPs at it's λmax and concentration .
Due to the λmax of Ag NPs is vary and depends on size, shape , distribution and time of reduction,it,s difficult to get accurate concentration using UV-Vis absorption spectroscopy. Weighing or EDS methods appear to be much more accurate.
I recently measured the Ag concentration using ICP-AES after synthesis of AgNP using microalgae. I used NaCl solution to precipitate unreacted Ag+ as AgCl and then measured the stable AgNP in the supernatant. Here is the article (it has detailed method). ICP-MS would give you more accurate results though.
https://www.mdpi.com/1420-3049/24/1/98
You can measure the Ag+ ions in a solution before and after the reduction.
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