Department of Basic Sciences and Environment, University of Copenhagen, Frederiksberg, C DK-1871, Denmark.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2009 Dec;26(12):1619-27. doi: 10.1080/02652030903225740.
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.
预计，源自可再生资源的生物聚合物将在适当的时候完全替代源自化石燃料的塑料，成为食品包装材料。在这种情况下，生物聚合物纳米复合材料是一个新兴的研究领域，因为这些材料可以表现出更好的机械和阻隔性能，并且更适合更广泛的食品包装应用。为此，丹麦战略研究理事会资助的一个名为“NanoPack”的项目正在研究天然或合成粘土纳米填料。为了检测和表征粘土纳米颗粒的大小，提出了一种组合不对称流场流分离（AF4）与多角度光散射检测（MALS）和电感耦合等离子体质谱（ICP-MS）的分析系统。在迁移研究中，我们测试了一种由聚乳酸（PLA）和 5%的 Cloisite30B（一种衍生化蒙脱石粘土）组成的纳米复合材料作为填充物。基于 AF4-MALS 分析，我们发现半径为 50 至 800nm 的颗粒确实迁移到了 95%乙醇中，这是用作食品模拟物的物质。然而，完整的串联 AF4-MALS-ICP-MS 系统表明，没有检测到任何特征粘土矿物，因此可以得出结论，迁移物中不存在粘土纳米颗粒。最后，通过离心实验，使用 AF4-MALS 对板状尺寸进行测量，计算出蒙脱石粘土的板状纵横比为 320。
