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Detection and sizing of nanoparticles in food additive E551 (silica)

Nov 07 2016

JRC scientists have proposed a systematic, sequential evaluation scheme involving the use of different techniques for the assessment of the presence of nanoparticles (NPs) in food-grade synthetic amorphous silica (SAS), usually coded as food additive E551.

Current EC Regulation, 1169/2011 on the provision of food information to consumers foresees indicating on the food product label if ingredients (e.g. additives) in the nanoform are used. The appropriate implementation of such legislation is based on the availability of reliable methods for detection and quantification of nanoparticles in food. SAS has been traditionally used as food additive under the code E551; however, there is still a lack of detailed methodologies for the determination of SAS’ particle size and concentration.
In this work, a methodological approach is proposed based on a set of systematic analyses of a variety of commercial E551 samples with various techniques such as Dynamic Light Scattering (DLS), Multi-Angle Light Scattering (MALS), Asymmetric Flow Field Flow Fractionation (AF4), Inductively Coupled Plasma Mass Spectrometry (ICPMS) and Transmission Electron Microscopy (TEM). The proposed sequential order is based primarily not only on the requirement of increasing the amount of information, achieving better resolution and greater sensitivity, but also on the increasing complexity, duration of analysis and cost.
Given that the dynamic size application range is limited by the minimum detectable size, all the techniques considered in this work can only be used as positive tests to indicate the presence of nanoparticles in the food additive samples.


Fractograms obtained after the injection of: A) all filtered samples by AF4-ICPMS applying the method targeting particles below 100 nm; B) detail of fractograms corresponding to pyrogenic SAS with SiO2-NPs standards; C) detail of fractograms corresponding to wet SAS with SiO2-NPs standards

Read more in: F. Barahona et al.: "Multimethod approach for the detection and characterisation of food-grade synthetic amorphous silica nanoparticles", J. Chromatogr. A.1432 (2016) 92-100, doi:10.1016/j.chroma.2015.12.058