Nanosized particles are frequently used in many different applications, especially TiO2 nanoparticles as
physical filters in sunscreens to protect the skin from UV radiation. However, concerns have arisen about
possible health issues caused by nanoparticles and therefore, the assessment of the occurrence of
nanoparticles is importantin pharmaceutical and cosmetic formulations. In a previous work of our group,
a method was presented to extract nanoparticles from O/Wemulsions. But to respond to the needs of dry
and sensitive skin, sunscreens of the water-in-oil emulsion type are available. In these, assessment of
present nanoparticles is also an important issue, so the present study offers a method for extracting
nanoparticles from W/O emulsions. Both methods emanate from the same starting point, which
minimizes both effort and cost before the beginning of the assessment. By addition of NaOH pellets and
centrifugation, particles were extracted from W/O emulsions and measured for their size and surface
area by laser diffraction. With the simple equation Q= A/S a distinction between nanoparticles and
microparticles was achieved in W/O emulsions, even in commercially available samples. The present
method is quick and easy to implement, which makes it cost-effective