Agglomeration... that's the biggest problem in PPTion technique.. ..

The only thing I kno is that it depends of a lot of factors, but the most important is how redispersable are your nanoparticles after the precipitation.

If you have a very aglommerated sample, you can try with the filtration method. You can try size separation columns or dialisis membranes, this is up to you.

Thank you sridhar, saurav and sadvador..............let me knw about statistics method to find gussian curve and particles.........is any publication ..........please send me.......doi........