title: Combining asymmetrical flow field-flow fractionation with light-scattering and inductively coupled plasma mass spectrometric detection for characterization of nanoclay used in biopolymer nanocomposites.
abstract: It is expected that biopolymers obtained from renewable resources will in due course become fully competitive with fossil fuel-derived plastics as food-packaging materials. In this context, biopolymer nanocomposites are a field of emerging interest since such materials can exhibit improved mechanical and barrier properties and be more suitable for a wider range of food-packaging applications. Natural or synthetic clay nanofillers are being investigated for this purpose in a project called NanoPack funded by the Danish Strategic Research Council. In order to detect and characterize the size of clay nanoparticulates, an analytical system combining asymmetrical flow field-flow fractionation (AF(4)) with multi-angle light-scattering detection (MALS) and inductively coupled plasma mass spectrometry (ICP-MS) is presented. In a migration study, we tested a biopolymer nanocomposite consisting of polylactide (PLA) with 5% Cloisite30B (a derivatized montmorillonite clay) as a filler. Based on AF(4)-MALS analyses, we found that particles ranging from 50 to 800 nm in radius indeed migrated into the 95% ethanol used as a food simulant. The full hyphenated AF(4)-MALS-ICP-MS system showed, however, that none of the characteristic clay minerals was detectable, and it is concluded that clay nanoparticles were absent in the migrate. Finally, by means of centrifugation experiments, a platelet aspect ratio of 320 was calculated for montmorillonite clay using AF(4)-MALS for platelet size measurements.
authors.affiliation: Department of Basic Sciences and Environment, University of Copenhagen, Frederiksberg, C DK-1871, Denmark.
authors.forename: B
authors.initials: B
authors.lastname: Schmidt
authors.forename: J H
authors.initials: JH
authors.lastname: Petersen
authors.forename: C
authors.initials: C
authors.lastname: Bender Koch
authors.forename: D
authors.initials: D
authors.lastname: Plackett
authors.forename: N R
authors.initials: NR
authors.lastname: Johansen
authors.forename: V
authors.initials: V
authors.lastname: Katiyar
authors.forename: E H
authors.initials: EH
authors.lastname: Larsen
mesh_terms: D000538:Aluminum Silicates; D001704:Biopolymers; D000077215:Clay; D004058:Diffusion; D005504:Food Analysis / Q000379:methods; D005506:Food Contamination / Q000032:analysis*; D018857:Food Packaging; D031521:Fractionation, Field Flow / Q000379:methods; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D053761:Nanocomposites / Q000032:analysis*; D010316:Particle Size; D012542:Scattering, Radiation
chemical_list: D000538:Aluminum Silicates; D001704:Biopolymers; D000077215:Clay