Bossert, David Urban, Dominic A. Maceroni, Mattia Ackermann-Hirschi, Liliane Haeni, Laetitia Yajan, Phattadon Spuch-Calvar, Miguel Rothen-Rutishauser, Barbara Rodriguez-Lorenzo, Laura Petri-Fink, Alke Schwab, Fabienne 2019-05-28 As the commercial use of synthetic amorphous silica nanomaterials (SiO2-NPs) increases, their effects on the environment and human health have still not been explored in detail. An often-insurmountable obstacle for SiO2-NP fate and hazard research is the challenging analytics of solid particulate silica species, which involves toxic and corrosive hydrofluoric acid (HF). We therefore developed and validated a set of simple hydrofluoric acid-free sample preparation methods for the quantification of amorphous SiO2 micro- and nanoparticles. To circumvent HF, we dissolved the SiO2- NPs by base-catalyzed hydrolysis at room temperature or under microwave irradiation using potassium hydroxide, replacing the stabilizing fluoride ions with OH−, and exploiting the stability of the orthosilicic acid monomer under a strongly basic pH. Inductively coupled plasma – optical emission spectroscopy (ICP-OES) or a colorimetric assay served to quantify silicon. The lowest KOH: SiO2 molar ratio to effectively dissolve and quantify SiO2-NPs was 1.2 for colloidal Stöber SiO2-NPs at a pH >12. Fumed SiO2-NPs (Aerosil®) or food grade SiO2 (E551) containing SiO2-NPs were degradable at higher KOH: SiO2 ratios >8000. Thus, hydrofluoric acid-free SiO2- NP digestion protocols based on KOH present an effective (recoveries of <84%), less hazardous, and easy to implement alternative to current methods. application/pdf https://folia.unifr.ch/global/documents/307956 https://folia.unifr.ch/documents/307956/files/fin_haf.pdf https://folia.unifr.ch/documents/307956/files/fin_haf_sm.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1038/s41598-019-44128-z info:eu-repo/semantics/openAccess License undefined Scientific Reports. - 2019, vol. 9, no. 1, p. 7938 info:eu-repo/classification/udc/54 A hydrofluoric acid-free method to dissolve and quantify silica nanoparticles in aqueous and solid matrices http://purl.org/coar/resource_type/c_6501