5 years ago



98 the distinction

98 the distinction between samples which contain engineered nanomaterials and those that do not. These methods will be characterised by minimal sample preparation, cost-efficiency and high throughput. More sophisticated, hyphenated methods will allow the unambiguous characterisation and quantification of engineered nanomaterials. These will include elaborate sample preparation, separation by field flow fractionation and chromatographic techniques as well as mass spectrometric and electron microscopic characterisation techniques. The developed methods will be validated using the well characterised food matrix reference materials that will be produced within the project. Small-scale interlaboratory method performance studies and the analysis of a few commercially available products claiming or suspect to contain engineered nanomaterials will demonstrate the applicability and soundness of the developed methods. References _______________________________________________ EFSA - European Food Safety Authority. 2009. The potential risks arising from nanoscience and nanotechnologies on food and feed safety (EFSA-Q-2007-124a). The EFSA Journal 958, 1-39. 1178620753812_1211902361968.htm

Quantitative analysis of the physical characteristics of manufactured silica nanoparticles (NPs) used in food by advanced transmission electron microscopy Pieter-Jan De Temmerman, Elke Van Doren, Michel Abi Daoud Francisco & Jan Mast CODA-CERVA, Groeselenberg 99, B-1180, Brussels, Belgium E-mail: Manufactured silicon dioxide (silica) nanoparticles (NPs) are chemically inert, pure white and free-flowing with a neutral pH. They do not affect the colour, taste, odor or nature of food. Silica NPs are applied in concentrations of up to 2 % of the end product weight to make granular and powdered food materials free-flowing, as anti-caking agents for food products high in oils or fats and to convert liquids into free flowing powders. Silica NPs are effective across a wide variety of food applications, including cheese, non-dairy creamers, food flavours, powdered drink mixes, seasonings and as tabletting aid for vitamin supplements. Physical characteristics of silica NPs are important factors to evaluate their effectivity and the possible health risk of their application. By its high resolution, transmission electron microscopy (TEM) is one of the few techniques that allow direct visualization of nanomaterials. Conventional sample preparation techniques coupled to TEM imaging and (semi)automatic, threshold-based detection of NPs in electron micrographs are evaluated to measure the physical properties of silica NPs used in food on a per-particle-basis, and standard operating procedures were developed. Conventional TEM imaging using a Tecnai Spirit TEM (FEI, Eindhoven, The Netherlands) operating at 120 kV allows directly visualizing the agglomeration state of the silica NP and the structure, size and shape of their composing primary subunits (Figure A). Digital micrographs were made using a 4*4 k Eagle CCD-camera (FEI) and stored in an iTEM database (Olympus, Münster, Germany) together with imaging and sample preparation data and with (intermediate) results. 99

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