Examination of primary aromatic amines content in polylactic acid straws and migration into food simulants using SERS with LC-MS

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2025-01, Vol.324, p.124997, Article 124997
• Main Authors: Zhang, Zhu-Rui, Chen, Ying, Wang, Zhi-Wei, Hu, Chang-Ying, Hu, Yuling, Xu, Xiaowen
• Format: Article
• Language: English
• Subjects: Drinking straws; Liquid chromatography-mass spectrometry; Migration study; Polylactic acid; Primary aromatic amines; Surface-enhanced Raman spectroscopy
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2024.124997

[Display omitted] •SERS rapidly screened & LC-MS accurately quantified PAAs in 18 brands of PLA straws.•2,4-TDA exceeded specific migration limits in 50% ethanol, raising safety concerns.•PAAs migration into 10% & 50% ethanol exceeded into 4% acetic acid in a short period.•Polymer additives including PBS & PBAT enhanced straws’ heat & hydrolysis resistance.•Migration mechanism into different food simulants were comprehensively discussed. Polylactic acid (PLA) straws hold eco-friendly potential; however, residual diisocyanates used to enhance the mechanical strength can generate carcinogenic primary aromatic amines (PAAs), posing health risks. Herein, we present a rapid, comprehensive strategy to detecting PAAs in 18 brands of food-grade PLA straws and assessing their migration into diverse food simulants. Surface-enhanced Raman spectroscopy was conducted to rapidly screen straws for PAAs. Subsequently, qualitative determination of migrating PAAs into various food simulants (4 % acetic acid, 10 % ethanol, 50 % ethanol) occurred at 70 °C for 2 h using liquid chromatography-mass spectrometry. Three PAAs including 4,4′-methylenedianiline, 2,4′-methylenedianiline, and 2,4-diaminotoluene were detected in all straws. Specifically, 2,4-diaminotoluene in 50 % ethanol exceeded specific migration limit of 2 μg/kg, raising safety concerns. Notably, PAAs migration to 10 % and 50 % ethanol surpassed that to 4 % acetic acid within a short 2-hour period. Moreover, PLA straws underwent varying degrees of shape changes before and after migration. Straws with poly(butylene succinate) resisted deformation compared to those without, indicating enhanced heat resistance, while poly(butyleneadipate-co-terephthalate) improved hydrolysis resistance. Importantly, swelling study unveiled swelling effect wasn’t the primary factor contributing to the increased PAAs migration in ethanol food simulant, as there was no significant disparity in swelling degrees across different food simulants. FT-IR and DSC analysis revealed higher PAAs content in 50 % ethanol were due to highly concentrated polar ethanol disrupting hydrogen bonds and van der Waal forces holding PLA molecules together. Overall, minimizing contact between PLA straws and alcoholic foods is crucial to avoid potential safety risks posed by PAAs.