Isolation and Quantification of Polyamide Cyclic Oligomers in Kitchen Utensils and Their Migration into Various Food Simulants

PLoS One. 2016 Jul 25;11(7):e0159547. doi: 10.1371/journal.pone.0159547. eCollection 2016.

Abstract

Small amounts of cyclic monomers and oligomers are present in polyamide (PA)-based kitchen utensils. In this study, we isolated eight PA-based cyclic monomers and oligomers from kitchen utensils made from PA6 (a polymer of ε-caprolactam) and PA66 (a polymer of 1,6-diaminohexane and adipic acid). Their structures were identified using high-resolution mass spectrometry and 1H- and 13C-nuclear magnetic resonance spectroscopy, and their residual levels in PA-based kitchen utensils and degree of migration into food simulants were quantified by high-performance liquid chromatography/mass spectrometry using purchased PA6 monomer and isolated PA66 monomers, and isolated PA6 and PA66 oligomers as calibration standards. Their total residual levels among 23 PA-based kitchen utensils made from PA6, PA66, and copolymers of PA6 and PA66 (PA6/66) ranged from 7.8 to 20 mg/g. Using water, 20% ethanol, and olive oil as food simulants, the total migration levels of the PA monomers and oligomers ranged from 0.66 to 100 μg/cm2 under most examined conditions. However, the total migration levels of the PA66 monomer and oligomers from PA66 and PA6/66 kitchen utensils into 20% ethanol at 95°C were very high (1,700 and 2,200 μg/cm2, respectively) due to swelling by high-temperature ethanol.

MeSH terms

  • Caprolactam / chemistry
  • Chromatography, Liquid
  • Cooking and Eating Utensils*
  • Hydrolysis
  • Magnetic Resonance Spectroscopy
  • Mass Spectrometry
  • Molecular Structure
  • Nylons / chemistry*
  • Polymers / chemistry*
  • Polymers / isolation & purification*

Substances

  • Nylons
  • Polymers
  • Caprolactam

Grants and funding

These authors have no support or funding to report.