title: Size analysis of nanoparticles extracted from W/O emulsions.
abstract: 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 important in pharmaceutical and cosmetic formulations. In a previous work of our group, a method was presented to extract nanoparticles from O/W emulsions. 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.
authors.affiliation: University of Vienna, Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Nagelreiter
authors.affiliation: Electron Microscopy Facility, Campus Science Support Facilities GmbH (CSF), Vienna Biocenter, Dr. Bohr-Gasse 3, 1030 Vienna, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Kotisch
authors.affiliation: Electron Microscopy Facility, Campus Science Support Facilities GmbH (CSF), Vienna Biocenter, Dr. Bohr-Gasse 3, 1030 Vienna, Austria.
authors.forename: T
authors.initials: T
authors.lastname: Heuser
authors.affiliation: University of Vienna, Department of Pharmaceutical Technology and Biopharmaceutics, Faculty of Life Sciences, Althanstraße 14, 1090 Vienna, Austria; University of Vienna, Research Platform "Characterisation of Drug Delivery Systems on Skin and Investigation of Involved Mechanisms", Althanstraße 14, 1090 Vienna, Austria. Electronic address: claudia.valenta@univie.ac.at.
authors.forename: C
authors.initials: C
authors.lastname: Valenta
mesh_terms: D002626:Chemistry, Pharmaceutical / Q000379:methods*; D004655:Emulsions / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013473:Sunscreening Agents / Q000737:chemistry; D013501:Surface-Active Agents; D013678:Technology, Pharmaceutical / Q000379:methods; D014025:Titanium / Q000737:chemistry
chemical_list: D004655:Emulsions; D013473:Sunscreening Agents; D013501:Surface-Active Agents; C009495:titanium dioxide; D014025:Titanium
keywords: Laser diffraction; Nanoparticles; Size estimation; W/O emulsion; Water-in-oil emulsion