Question

How to calculate concentration of nanoparticles through dls?

Answer 1

 i guess you want to calculate the conc of nanoparticles (nM/pM) in the colloidal solution. If yes and NP are spherical in shape, then you can use the following steps:

a) You know the weight of gold taken for NP synthesis (Au only, not gold salt) = W

b) Density of gold = 19.3 gcm-3

c) Now you calculate the volume of gold taken = W/9.320

d) Calculate the average size of nanoparticles using TEM (make sure nanoparticles are monodispersed) (2R)

e) Calculate the volume of a single nanoparticle (assuming sphere) = 4x(pi x R^3)/3 = V

f) You can calculate the number of particles in colloidal solution (N) = (W/9.32) / V

g) Calculate the conc of NP = N / Final volume of colloidal solution