![]() A major reason for the lack of knowledge in biomedical sciences on SiO 2 nanoparticle (SiO 2-NP) cell interactions or long-term fate and effects in the body 2 is the costly, time-consuming, and hazardous method required for the analysis of Si. However, the analysis of particulate silica species (here termed SiO 2) is challenging. Several million tons of this material are produced each year 1. Knowing the concentrations of amorphous silica particles is essential in numerous areas of science and technology. ![]() Thus, hydrofluoric acid-free SiO 2-NP digestion protocols based on KOH present an effective (recoveries of >84%), less hazardous, and easy to implement alternative to current methods. Fumed SiO 2-NPs (Aerosil ®) or food grade SiO 2 (E551) containing SiO 2-NPs were degradable at higher KOH: SiO 2 ratios >8000. The lowest KOH: SiO 2 molar ratio to effectively dissolve and quantify SiO 2-NPs was 1.2 for colloidal Stöber SiO 2-NPs at a pH >12. Inductively coupled plasma – optical emission spectroscopy (ICP-OES) or a colorimetric assay served to quantify silicon. To circumvent HF, we dissolved the SiO 2-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. We therefore developed and validated a set of simple hydrofluoric acid-free sample preparation methods for the quantification of amorphous SiO 2 micro- and nanoparticles. ![]() ![]() An often-insurmountable obstacle for SiO 2-NP fate and hazard research is the challenging analytics of solid particulate silica species, which involves toxic and corrosive hydrofluoric acid (HF). As the commercial use of synthetic amorphous silica nanomaterials (SiO 2-NPs) increases, their effects on the environment and human health have still not been explored in detail. ![]()
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