Thanks Gaser Nagah,

In fact the data shown in my question is just from papers I have read, the issue is to translate what is in a paper to develop my own method in which the conc. is less than 10mM. Then, I have the concentration of AgNO3, how and why to calculate the molar ratios for reacting substances.  

Because, it seems like I am going to prepare a separate solutions with those molar ratios.You can just refer to the attached article.

Thanks again.

Although I am not working extensively with metallic NP, I found this recipe to be quite successful in the formulation of Ag NP, with a size of approximately 10-15 nm.

SOLUTION 1:

650 mg PVP

500 mg NaOH

3 g glucose

7.5 ml MilliQ

SOLUTION 2:

5 mg AgNO3

2.5 ml MilliQ

1. Bring both solutions at approximately 60°C.

2. SOLUTION 1 will turn yellow when the temperature is reached.

3. Add SOLUTION B into SOLUTION A dropwise, under mild stirring. The suspension will turn brown/rusty/dark silver.

4. Keep at 60°C for 30 minutes, then cool down.

5. Centrifuge at 21000 g for 30 minutes. Wash with water. Repeat 3x.

The amounts are in grams, but you can try and figure out the molar concentrations. I rather not use formaldehyde as reducing agent though, glucose works well enough for me. The final Ag concentration is around 3 mM

Dear     Marco Emanuele Favretto,

That is great. I am gaining new insight and confidence, as time goes. Thank you for your good contribution.

Silver nanoparticles will take you a few reactions to get right, they are tricky to get exact, but eventually the reaction becomes quite trivial, so my first suggestion is to just try a few times. 

I second everything that Gaser Nagah said above. I would also add too, that the rate of addition of the reducing agent can also make a difference. There can be a big difference in the product between adding dropwise, or simply pouring everything together. Again, this comes down to what I said about trying it a few times. 

Good luck.

Thanks Alvin for your contribution. It awakes my mind for achieving.