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New Metrological Approach for Sizing Silica Nanoparticles by Dynamic Light Scattering with Applicability to Various Food Samples

Abstract A new and simple methodology has been developed on the use of dynamic light scattering for sizing silica nanoparticles and detecting their presence or absence in several food samples, namely fruit juices and sweeteners. Size confirmation of four nanosilica standards (20, 50, 80 and 100 nm) was performed with an error percentage lower than 3.5% and low concentration levels (a few mg L−1) were detected by dynamic light scattering, demonstrating the excellent sensitivity of this technique for characterizing these small nanoparticles present at low values. Moreover, no significant differences in size were observed in the concentration range assayed in this work. The applicability of this new approach has been successfully demonstrated in food items separately spiked with nanosilica of each size. No matrix effects were observed in the correlograms obtained by dynamic light scattering. The results showed that all of the samples contain a remarkable population of nanoparticles from an unknown source, increasing the interest of these findings.