Gajdosechova & Loeschner 2023 — Nanoparticles as trace element species in food
This review addresses the emerging recognition that trace elements in food exist not only as dissolved ionic species or simple organometallics but also as nanoparticulate forms. The authors review evidence for nanoparticulate arsenic, mercury, and selenium species in foods, the analytical techniques (HPLC-ICP-MS, AF4-ICP-MS, SEC-ICP-MS) capable of characterizing them, and the implications for regulatory risk assessment frameworks that currently assume bioavailability from purely dissolved species. The paper is directly relevant to arsenic and mercury speciation methodology and to the interpretation of total-element measurements in food.
Key numbers
- Scope: Review covering approximately 2015 to 2023 literature on nanoparticulate trace elements in food
- Key matrices discussed: fish and seafood (Hg nanoparticles in tuna, swordfish), vegetables and grains (As nanoparticles), seleniferous plants and supplements (Se nanoparticles)
- Finding: A non-trivial fraction of total arsenic in some food matrices appears as arsenite nanoparticles or nanoparticle-bound organoarsenicals rather than free ionic iAs or DMA/MMA; the fraction varies by matrix and processing
- Hg nanoparticles: mercury sulfide nanoparticles (metacinnabar, HgS) detected in fish tissue; bioavailability of HgS nanoparticles lower than MeHg, potentially explaining discrepancies in toxicokinetic modeling from total-Hg data alone
- Se: selenium nanoparticles (SeNPs) in garlic and other seleniferous plants; bioavailability different from selenomethionine
- Analytical challenge: HPLC-ICP-MS speciation protocols designed for ionic species may misclassify nanoparticulate forms; size-exclusion and field-flow fractionation methods needed
- Dissolution behavior in GIT: nanoparticle dissolution during in vitro GIT digestion affects bioaccessibility estimates; current in vitro bioaccessibility methods may not accurately model nanoparticulate forms
Methods (brief)
Narrative review; no primary experimental data. References analytical methods including: AF4-ICP-MS, SEC-ICP-MS, SP-ICP-MS (single particle ICP-MS), TEM-EDX for particle characterization. LOD and method-specific information drawn from cited primary literature.
Implications
Certification: Nanoparticulate speciation adds complexity to iAs and tHg measurement interpretation. Total-element measurements may overestimate or underestimate bioavailable toxic species if nanoparticles are present. This is a frontier methodological issue for food testing laboratories using standard ICP-MS or HPLC-ICP-MS protocols.
Courses: Key teaching case for the distinction between total measurement and bioavailable/toxic speciation; demonstrates that the field is advancing beyond simple inorganic vs. organic speciation.
App: Low near-term relevance; app should default to standard ICP-MS data for ingredient contamination profiles.
Microbiome: Not applicable.