available at gandipuram

Why don't you synthesize in laboratories

I am wondering why you have ppm with the particles sizes. Are you making a solution or separating the particles in form of a powder?

In the second case, you must note that it is almost impossible to have a powder of exactly same particle sizes. I mean you will always end up with a range of sizes, for e.g. from 50 microns to 100 microns or 100 to 200 microns. You can achieve this in a lab if you have right sizes of the sieves. All you need to do is sieve the powder through the larger sieve (for e.g. 200 microns). Collect all the residue and filter again through a smaller sieve (for e.g. 100 microns). The particles left over on the second sieve (100 microns) will be between 100 to 200 microns. 

https://en.wikipedia.org/wiki/Sieve

Thank you for the your great information Hassan Khawaja