Better methodsPublished on 26.07.2019

Cleaner, safer analysis for silicon dioxide nanoparticles

Researchers at the Adolphe Merkle Institute (AMI) have developed a new protocol to quantify silica nanoparticles, often found in processed food, that is safer, more environmentally friendly, and less hazardous than current methods.

Silica nanoparticles are more common than most people think. They are present for example as part of food grade silica (SiO2), otherwise known as E551 on labels and packaging, and used in a variety of products such as table salt or protein powders to avoid clumping. There has been however little research into its potential effects on the environment or human health.

This lack of research is largely due to the fact that current analysis protocols call for the use of highly toxic and corrosive hydrofluoric acid. It requires the usage of heavy-duty gloves, face shields and chemical aprons, and the acid also inflicts major wear and tear on analytical equipment, especially glass and quartz elements. So, while it is clearly important to establish the presence and quantity of silica nanoparticles in consumer products, laboratories often prefer to avoid analysis using the hydrofluoric acid method.

To make silica nanoparticle analysis more accessible, David Bossert and co-workers from the AMI BioNanomaterials group switched from the acid to a base, in this case potassium hydroxide that can also dissolve silica, but causes less corrosion on instrument elements, and is less hazardous to use. This less aggressive solution has a number of advantages, not least that it can be used in research and development, for example to develop environmentally benign nanofertilizers, or drugs based on silica nanoparticles.

“This research is a contribution to safer, more economic, and more ecological laboratory procedures, and will allow analysis of silica nanoparticles by labs that aren't equipped to handle the hydrofluoric acid protocol, making it available to a broader research community,” says Dr. Fabienne Schwab, who led the research together with AMI Prof. Alke Fink. The concept of the silica analysis method is applicable to a broad range of sample matrices, and is expected to extend knowledge about the presence, transport, and degradation of silica nanoparticles in the environment, as well as in many consumer products including food.

The results of the study were recently published in the leading open-access journal Scientific Reports. This research was funded by the Swiss National Science Foundation, the Adolphe Merkle Foundation, and the University of Fribourg.


Bossert, D., Urban, D.A., Maceroni, M., Ackermann-Hirschi, L., Haeni, L., Yajan, P., Spuch-Calvar, M., Rothen-Rutishauser, B., Rodriguez-Lorenzo, L., Petri-Fink, A., Schwab, F. A hydrofluoric acid-free method to dissolve and quantify silica nanoparticles in aqueous and solid matrices, Scientific Reports, 2019, 9, 1, 7938