Cyclic oligomers in polyamide for food contact material: quantification by HPLC‐CLND and single‐substance calibration

Abstract

Cyclic oligomers are the major substances migrating from polyamide (PA) food contact materials. However, no commercial standards are available for the quantification of these substances. For the first time the quantification of cyclic oligomers was carried out by HPLC coupled with a chemiluminescence nitrogen detector (CLND) and single-substance calibration. Cyclic monomer (MW = 226 Da) and dimer (MW = 452 Da) of PA66 were synthesised and equimolar N detection of CLND to synthesised oligomers, caprolactam, 6-aminohexanoic acid (monomers of PA6) and caffeine (a typical nitrogen calibrant) was proven. Relative response factors (UVD at 210 nm) referring to caprolactam were determined for cyclic PA6 oligomers from dimer to nonamer, using HPLC-CLND in combination with a UVD. A method for quantification of cyclic oligomer content in PA materials was introduced using HPLC-CLND analysis and caffeine as a single nitrogen calibrant. The method was applied to the quantification of cyclic PA oligomers in several PA granulates. For two PA6 granulates from different manufacturers markedly different oligomer contents were analysed (19.5 versus 13.4 g kg⁻¹). The elution pattern of cyclic oligomers offers the possibility of identifying the PA type and differentiating between PA copolymers and blends.

The TTC Approach in Practice and its Impact on Risk Assessment and Risk Management in Food Safety. A Regulatory Toxicologist's Perspective

“…BfR has begun to analyze the hydrolysis behavior of different oligomers formed from polyamide. [38,39] Case 4: Alternaria To xins in Crops,…”

Migration of Cyclic Monomer and Oligomers from Polyamide 6 and 66 Food Contact Materials into Food and Food Simulants: Direct Food Contact

“…Commercial PAs contain up to 2% cyclic monomer and oligomers, which are formed by side reactions during PA synthesis. [1][2][3] Figure 1 shows structures of some of these substances. An explanation on nomenclature is given in a previous article.…”

“…An explanation on nomenclature is given in a previous article. 1 Cyclic PA monomer and oligomers migrate from PA FCM into food and food simulants. In EU regulation 10/2011, 4 a specific migration limit (SML) is set out for starting substances, such as caprolactam (SML = 15 mg kg À1 ).…”

Quantitative analysis of cyclic dimer fatty acid content in the dimerization product by proton NMR spectroscopy

“…To analyze the dimer acid, several methods including high-performance liquid chromatography (HPLC) [13][14][15][16], gas chromatography [17], and capillary electrophoresis [18] have been employed for the quantitative determination of dimer acids. However, in the case of complex mixtures, these methods require http://dx.doi.org/10.1016/j.saa.2015.04.099 1386-1425/Ó 2015 Elsevier B.V. All rights reserved.…”

“…However, in the case of complex mixtures, these methods require http://dx.doi.org/10.1016/j.saa.2015.04.099 1386-1425/Ó 2015 Elsevier B.V. All rights reserved. a complicated and time-consuming pre-treatment to extract and concentrate each target compound from the mixture to prepare high purity analytical grade target materials [15,16].…”