Engineered nanoparticles are commonly used in a number of industrial and consumer sectors, including cosmetics, personal care products and even some foodstuffs. Among food additives permitted in Europe, the use of synthetic amorphous silica particles has recently captured the attention of the scientific community, since the European Commission Directive 2008/84/EC 20.9.2008 which authorises its uses has neglected the possible hazards related to particle size of the primary grains, falling into the nano size range. In order to determine the properties and potential biological effects of nano-particles, physico-chemical particle characterization information is required, for example particle size, particle shape, aggregation grade, solubility, elemental purity and surface area, surface reactivity. At present, there are no standardized methodologies that can provide all these parameters at one time; rather different analytical methods must be used synergically to obtain reliable data. In this study, four types of SiO2, available on the market as additives in food and personal care products, were firstly size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organised in clusters or aggregates of different dimension. Secondly, to set-up a protocol for determining insoluble (silica) particles in foodstuffs, a nearly silica-free commercial powder of instant barley coffee was enriched with about 0.25% w/w of a SiO2 sample just characterised. The SdFFF technique, in conjunction with SEM observations, allowed to identify the added SiO2 particles and verify the new particle size distribution. Finally, some commercial products counting E551 or silicon dioxide among their ingredients were mineralized and analyzed through graphite furnace atomic adsorption spectroscopy (GFAAS) to determine their Si content, expressed as SiO2 percentage; the insoluble particles were extracted from the products with the highest Si concentration, fractionated by SdFFF and observed by SEM for size characterization. To ascertain that the sorted particles were silica, GFAAS analyses were performed on collected fractions.
Sedimentation field flow fractionation size characterization of silica particles used in the food industry
CONTADO, Catia;PASSARELLA, Martina
2013
Abstract
Engineered nanoparticles are commonly used in a number of industrial and consumer sectors, including cosmetics, personal care products and even some foodstuffs. Among food additives permitted in Europe, the use of synthetic amorphous silica particles has recently captured the attention of the scientific community, since the European Commission Directive 2008/84/EC 20.9.2008 which authorises its uses has neglected the possible hazards related to particle size of the primary grains, falling into the nano size range. In order to determine the properties and potential biological effects of nano-particles, physico-chemical particle characterization information is required, for example particle size, particle shape, aggregation grade, solubility, elemental purity and surface area, surface reactivity. At present, there are no standardized methodologies that can provide all these parameters at one time; rather different analytical methods must be used synergically to obtain reliable data. In this study, four types of SiO2, available on the market as additives in food and personal care products, were firstly size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organised in clusters or aggregates of different dimension. Secondly, to set-up a protocol for determining insoluble (silica) particles in foodstuffs, a nearly silica-free commercial powder of instant barley coffee was enriched with about 0.25% w/w of a SiO2 sample just characterised. The SdFFF technique, in conjunction with SEM observations, allowed to identify the added SiO2 particles and verify the new particle size distribution. Finally, some commercial products counting E551 or silicon dioxide among their ingredients were mineralized and analyzed through graphite furnace atomic adsorption spectroscopy (GFAAS) to determine their Si content, expressed as SiO2 percentage; the insoluble particles were extracted from the products with the highest Si concentration, fractionated by SdFFF and observed by SEM for size characterization. To ascertain that the sorted particles were silica, GFAAS analyses were performed on collected fractions.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
