Monitoring the extraction of additives and additive degradation products from polymer packaging into solutions by multi-residue method including solid phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry analysis

International audienceThe use of polymer materials in industry for product packaging is increasing. The presence of additives in the polymer matrix enables the modification or improvement of the properties and performance of the polymer, but these industries are concerned regarding the extractability of these additives. The quantification of these additives is particularly challenging because of the presence of these substances as contaminants in all the analytical equipment and the diversity of their physicochemical properties. In this context, a multi-residue analytical method was developed for the trace analysis of the twenty main additives (and their degradation products) authorized in plastic products such as pharmaceutical packaging (e.g., antioxidants, release agents, and light absorbers). This analytical method consisted of a solid phase extraction (SPE) followed by an analysis using ultra-high performance liquid chromatography coupled to a tandem mass spectrometer (UHPLC-MS/MS). A comparison of two ionization interfaces and the optimization of the extraction procedure were discussed. The influence of the quality of the solvent type (distilled versus not distilled) and the nature of the SPE cartridges (Polypropylene versus Teflon®) were demonstrated. The optimized method exhibited a quantification limit lower than 20 ng mL−1 and recoveries between 70 % and 120 % for all compounds. Finally, the method was validated according to the ICH directive and was subsequently applied to the extraction of polymers under different pH conditions and storage temperatures. To the best of our knowledge, this study presents the first methodology allowing the simultaneous quantification of 24 additives at low ng mL−1

Using various techniques to characterize oxidative functionalized and aminosilanized carbon nanotubes for polyamide matrix

The main purpose of this study was to reveal usability of various characterization techniques for certain aspects of surface functionalized multi-walled carbon nanotubes. Surfaces were first oxidative functionalized by sulphuric acid/nitric acid mixture, then aminosilanized by gamma-aminopropyltriethoxysilane. Chemical groups formed on carbon nanotubes due to these surface treatments were characterized by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and also energy dispersive spectroscopy. Morphological changes and crystal structure of surface-treated carbon nanotubes were analyzed by scanning electron microscopy and X-ray diffraction, respectively. Thermogravimetric analysis was also used to observe thermal degradation of the chemical groups formed on the nanotube surfaces. In the second part of the study, Polyamide-6 nanocomposites were produced by using unmodified and surface functionalized carbon nanotubes. Transmission electron microscopy indicated that surface functionalization improves distribution of carbon nanotubes in the matrix, while flexural tests revealed that strength and modulus values could be increased as much as 30% and 40%, respectively, due to enhanced interfacial bonding between the matrix and nanotubes