Online-coupling of AF4 and single particle-ICP-MS as an analytical approach for the selective detection of nanosilver release from model food packaging films into food simulants

Abstract

It is of utmost importance, that reliable exposure data about the migration behavior of nanoparticles are collected in order to provide adequate information for the safety assessment of engineered nanoparticles (ENPs) used in the food packaging sector. The objective of this study was to evaluate the migration behavior of silver nanoparticles (AgNPs) from model food packaging films with varying nanosilver content into three different food simulants (water, 10% ethanol and 3% acetic acid). The overall silver migration determined by classical inductively coupled plasma mass spectrometry (ICP-MS) analysis was dependent on the silver content of the films, the food simulant used and the contact time and temperature applied. Furthermore, single particle ICP-MS analysis was applied in order to detect and quantify migrated AgNPs selectively. As coexistent silver ions in the migration samples had an impedient effect (decreased signal-to-noise ratio), an optimized analytical approach was developed by online-coupling of asymmetric flow field flow fractionation (AF4) to single particle-ICP-MS. The enrichment of the nanoparticle fraction and simultaneous reduction of the ionic background via AF4 resulted in a clearly improved ICP-MS detection sensitivity, which enabled a more refined identification and size characterization of the migrated silver species. Scanning transmission electron microscopy (STEM) and energy-dispersive x-ray spectroscopy (EDS) confirmed independently the presence of AgNPs and silver/polymer heteroaggregates in the migration samples.