It seems as if nanoparticles are everywhere these days. The only problem is there is no perfect way to determine the size of these nanoparticles. Microscopy works great,but it is time consuming and expensive to determine the primary or aggregate particle size. Automated instruments, such as dynamic light scattering (photon correlation spectroscopy), work well if the nanoparticles are in a colloidal suspension. Recently, Micromeritics Analytical Services began calculating a primary particle size of nanoparticles from a measured BET surface area result.