You definitely want to go with AA; the concentrations you are dealing with are way beyond ICP-MS concentrations. If you have access to a ICP-OES (optical emission) that would be preferable; if not, the ease of use and cost of an AA is hard to beat. You can easily detect 10 ppb (ug/L) concentrations of silver on an AA, so sensitivity is really not an issue

You'll have to be careful in your preparation steps to make sure that you dissolve the silver and don't lose it to the container. Keep away from HCl; use high purity nitric acid

I suppose ICP-MS is more sensitive than AAS method. ICP-MS should do.

Thanks.

Good luck

ICPMS or ICP-OES is best to determine the metal concentration.

ICPMS has much better sensitivity then AAS for Ag analysis and therefore is the recommended method.

You definitely want to go with AA; the concentrations you are dealing with are way beyond ICP-MS concentrations. If you have access to a ICP-OES (optical emission) that would be preferable; if not, the ease of use and cost of an AA is hard to beat. You can easily detect 10 ppb (ug/L) concentrations of silver on an AA, so sensitivity is really not an issue

You'll have to be careful in your preparation steps to make sure that you dissolve the silver and don't lose it to the container. Keep away from HCl; use high purity nitric acid

Thank you so much all

If high concentration of Ag is expected. It is best to digest the Ag nanoparticles in HNO3 and do further dilution before analysis. Either ICPMS. ICPOES or AAS will do the job well.

For, high concentration of Ag, you may go for AAS also.

Hi Alham.

Do you want to measure Ag concentration in solution or AgNPs? With those techniques you can only measure the silver free concentration. If you want to measure nanoparticles you should use single particle ICP-MS (sp-ICP-MS) or other techniques such as FFF-ICP-MS.

Did you think of graphite fournace - atomic absorption spectrometry? It might have sufficiently low detection limits...

I think too many people are concerned with detection limits here. Yes, ICP-MS has a lower detection limit, however your application does not necessarily require this as you will have semi macro amounts of particles. If it is the total silver concentration you are after, then after dissolution in high purity nitric acid and dilution to the best estimated concentration range, AAS is fine, is the cheapest and simplest, and has very good DL for silver (< 10 micrograms/litre by flame AA) .

For nanoparticle counting, you will require an ICP-MS with a very fast integration time for SP-ICP-MS. Perkin Elmer do a suitable instrument, but it is not a simple technique if you are unfamiliar with ICP-MS. It is also possible to get rough estimates of particle size and shape     

I support the opinion of Henry Foden 

Dear Jose Antonio Carrero ,

I am interested in measuring the mass concentration (Ag) for a highly pure AgNPs suspension and compare with already commercial AgNPs measurements like the attached product.

So do you think the attached pdf had reported  the free silver concentration or only the silver nano particle concentration?? because i cant recognize what type of concentration is it??

i want to measure the same type.

best regards

Hi Alham

I'd support the ICPMS approach and I disagree with Henry Foden. sp-ICPMS can be done with most ICPMS available today. Short integration times are an advantage but not mandatory when looking at 45 nm particles. the sp-ICPMS approach will also allow you to distinguish the dissolved fraction (continuous background signal) from the particle fraction (occasional spikes) as long as the dissolved fraction is small enough so that the background intensity does not overprint the particle spikes. A serial dilution of the suspension can help to distinguish that further since the concentration of the dissolved solver will decrease while the spike intensities should remain constant and only occur less frequently.

It will also allow you to determine the particle number concentration and mass distribution but you cannot determine particle shape directly.

Hope this helps

Bodo

And regarding the certificate you mention, I'd believe that the concentration refers to the silver as NP.  It is not made clear whether there could be a non-NP silver fraction and an analysis after digestion will not allow to distinguish but I would think that that is rather unlikely and if so, the fraction should be small.

It will be more difficult to detect the individual 20 nm NPs using sp-ICPMS because of sensitivity though. Reported lowest detectable size limits for silver NPs are in the range of 30 nm using sp-ICPMS.

Bodo

Dear Alham,

The concentration that appears in the pdf you have attached is the silver mass concentration in the nanoparticle.You can use ICP-MS in standard mode to calculate de mass concentration of your NPs.

Best regards.

I agree with Mark Krause if you are quantifying total silver. As he stated, selection of the proper acid matrix is critical when silver is involved.

Greetings to you Alham Walid.

What is or are the question/s we should be answering?

1) Total silver as per dissolution measurements?

2) Dissolved silver i.e. "background" levels as per Bodo's reply?

3) Total silver nanoparticles per volume of liquid/matrix or other unit?

4) Silver concentration in the individual nano particles?

Please specify.

Dear Jose Antonio Carrero,

Thank you so much , that was very helpful.

Best Regards

AA will give you total silver concentration. If you want nanoparticle concentration, sp-ICPMS (single particle detection) is the way to go..although labor intensive.. the key is to adequately dilute the solution so you do not have overlapping nanoparticle events.

Thank you all for helping me 

Alham

I agree with Mark. I recommend adding Nitric Acid and a digestion (open heating or Microwave) step to avoid interferences due to the particles in the graphite tube.

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

I aggree. ICP-OES themes to be as accurate as ICP-MS.