Using single-particle ICP-MS for unravelling the effect of type of food on the physicochemical properties and gastrointestinal stability of ZnONPs released from packaging materials

Abstract

This article discusses the application of Single-Particle Inductively Coupled Plasma Mass Spectrometry (SP-ICP-MS) to study the effect of different types of food (orange juice and chicken breast) on the fate of zinc oxide nanoparticles (ZnONPs) migrated from two widely employed food packaging materials (polyethylene terephthalate (PET) and low density polyethylene (LDPE)). The gastrointestinal stability of ZnONPs was also evaluated. The idea behind this study is to track for first time the transformations underwent of nanoparticles in the different steps of their route from packaging to the consumer. The presence of high amount of dissolved zinc in the samples notably influenced size detection limit and the accuracy of SP-ICP-MS measurements. The diameter limits of detection (LODd) were 26 nm, 95 nm, 108 nm and 129 nm for aqueous solution, chicken breast extract and for oral and intestinal extracts, respectively. ZnONPs characterization in juice was not possible with SP-ICP-MS due to nanoparticles size was below LODd. Besides difficulties, SP-ICP-MS after extraction with Tris-HCl allowed us to determine that a 72% of the ZnONPs that migrated to chicken breast were smaller than 95 nm. Complementary to SP-ICP-MS, transmission electron microscopy (TEM) enabled to detect small nanoparticles (<3 nm). The combination of TEM and SP-ICP-MS measurements indicated that nanoparticles in chicken reach the intestine wall as small particles (<10 nm), as aggregates (>200 nm) and as ionic zinc whereas in case of juice only small nanoparticles (<3 nm) and ionic zinc were detected in the intestinal step.