A set of four reference materials for the detection and quantification of silica nanoparticles (NPs) in food was produced as a proof of principle exercise. Neat silica suspensions were ampouled, tested for homogeneity and stability, and characterized for total silica content as well as particle diameter by dynamic light scattering (DLS), electron microscopy (EM), gas-phase electrophoretic molecular mobility analysis (GEMMA), and field-flow fractionation coupled with an inductively coupled mass spectrometer (FFF-ICPMS). Tomato soup was prepared from ingredients free of engineered nanoparticles and was spiked at two concentration levels with the silica NP suspension. Homogeneity of these materials was found sufficient to act as reference materials and the materials are sufficiently stable to allow long-term storage and distribution at ambient temperature, providing proof of principle of the feasibility of producing liquid food reference materials for the detection of nanoparticles. The spiked soups were characterized for particle diameter by EM and FFF-ICPMS (one material only), as well as for the total silica content. Although questions regarding the trueness of the results from EM and FFF-ICPMS procedures remain, the data obtained indicate that even assigning values should eventually be feasible. The materials can therefore be regarded as the first step towards certified reference materials for silica nanoparticles in a food matrix.
Engineered nanoparticles Colloidal silica Reference material production
1.European Commission, Joint Research CentreInstitute for Reference Materials and Measurements (IRMM)GeelBelgium
2.Department of Environmental GeosciencesUniversity of ViennaViennaAustria
3.The Food and Environment Research AgencyYorkUK
4.Environment DepartmentUniversity of YorkYorkUK
5.Institute of Advanced Chemistry of Catalonia, Consejo Superior de Investigaciones Científicas (IQAC-CSIC) and Centro de Investigaciones Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN)BarcelonaSpain
6.Institute of Chemical Technologies and Analytics, Research Group Bio- and Polymer AnalysisVienna University of TechnologyViennaAustria