Is there a method to determine how much silver was reduced into nanoparticles? If so, which methods can you suggest?
Yes you could try X-Ray photo electron spectrometry (XPS). You will identify Ag and Ag+ with a bindind energy shift (eV) toward more energetic.
hello Fateme, these nano shows plamon around 440 nm, and coloidal shows pick at 300 nm, but I can not differentiate it when I have nano... maybe derivative UV... thanks)
You could use the surface plasmon to make sure you have your nanoparticles. For the content of Ag+, you can use a small portion of solution and do a titration to get Silver Chloride
Actually, ICP is very selective and accurate than titration; however, ICP give you information about all the Ag form as one result, you may find only the total Ag not the Ag+ and Ag separately.
Interesting question, We use to believe that starting with let's say 1mM ionic silver all was converted to metallic silver at the time 420 nm plasmon doesn't increase so Ag metallic concentration is 1mM after reaction ends but we haven't ever checked out by any method.
yes, I was asked in a congress about it and also in my quali exam... for industry it is necessary to know , for me as well =)
electro-chemical methods can also be applied .......however XPS is the preferable method owing to its sensitivity and accuracy..
XPS is the best way to measure Ag+ and Ag(0) with energy shift. But another indirect way is thr' ICP. Here you know the initial conc. of Ag+ used as precursor for AgNP synthesis..... after synthesis centrifuge the well mixed solution at high speed (abt 15000 rpm) for 20-30 min and measure the concentration of Ag+ in the supernatent. The difference is an approximate calculation for conversion of Ag+ to Ag(0). Or as Jhony suggested, go for titration to analyse Ag+.
Good luck dude....... Enjoy the thrill of experimenting.......
I have recently differentiate Ag+ and Ag0 using X-Ray photo electron spectrometry (XPS). The binding energies of the Ag 3d5/2 peaks are around 368 eV, and those of the Ag 3d3/2 peaks are in the 375 eV region. The shift in binding energy of Ag 3d5/2 relative to the bulk Ag (368.3 eV) could indicate a silver oxidation. For exemple in my case the core Ag 3d5/2 for Ag+ in Ag2O was 367.2 eV and Ag0 was 368.3 eV. The develop of a positive charge above the Ag0 state causes a negative energy binding shift (around 367 eV in Ag2+ species such as AgO). However, the chemical shift of Ag3d peaks does not often allow to clearly distinguish between the different chemical states of Ag, especially for the binding energies of Ag0 and Ag+ that are very close. The modified Auger parameter instead gives more informations:
http://www.uksaf.org/data/ag.html
Modified Auger parameter is an important energy parameter for identifying the chemical state of elements where chemical shift is very small or comparable with the energy resolution of the instrument. The parameter is calculated by adding the binding energy of the most intense photoelectron peak with the kinetic energy of the sharpest Auger peak.
Modified Auger parameter around 723-724.4 eV was attributed to Ag+ when in the range 725–728 eV, indicate that Ag is present in metallic state.