Silver Nanoparticles by ICP-OES

I use our ICP-OES to analyze digested soil samples. One of my colleagues recently asked if I could do an analysis of Ag-nanoparticle (NP) deterioration at various pH's. I've analyzed silver ions in nitric acid solutions, but I don't know anything about working with neutral/basic pH matrices. Is that possible? Is it possible to select conditions where only ions (not NP) will be analyzed, or will I have to filter out the NP to determine how much deterioration to free ions has occurred?

Great questions.  We have found that a particle that will pass through a 0.1 micron Millipore filter will behave as if it is in solution.  This general observation can be found in the literature on work done with ‘slurry nebulization’ ICP-OES where solid samples are treated in some manner to form colloidal suspensions/slurries that are then put through a pneumatic nebulization system.  I would expect your Ag nanoparticles to behave very well.  When the Ag hits the plasma it will not matter if it is an ion or an atom i.e. it will be overwhelmed by the high level of electrons in the plasma and the distribution of atom and ion atoms will be the same regardless of the form in solution.  I hope this makes sense but feel free to call with any questions, or concerns.

Serving you in chemistry,

Paul R. Gaines, Ph.D.
CEO of Inorganic Ventures & Fellow Chemist

DISCLAIMER: Advice offered by the chemists at Inorganic Ventures is intended for the individual posing the question. Feel free to contact us to verify whether these suggestions apply to your unique circumstances.