Migration of non-intentionally added substances from thermoplastic polyurethane hydration packs under realistic and repeated-use conditions

Abstract

Thermoplastic polyurethane (TPU) hydration packs are widely used for fluid storage in demanding scenarios such as outdoor endurance sports and military operations, where repeated use and prolonged contact with water are common. However, limited information is available on the chemical stability of TPU materials and their behaviour under realistic usage conditions. This study investigates the migration of volatile and non-volatile compounds from commercial and used TPU pouches under conditions simulating real use. Advanced analytical techniques (SPME-GC-MS and UPLC-QTOF) were applied to characterize migrants across different food simulants (10% ethanol, 3% acetic acid, tap water, and mineral water), temperatures (40 and 70 °C), contact times (6 and 24 h), and repeated use cycles. Results revealed a complex migration profile, with 28 non-volatile and nearly 114 volatile compounds identified. The occurrence of compounds such as isophorone, tetrahydrofuran (THF) oligomers, and triphenylphosphine oxide (TPPO) suggests that both material composition and degradation processes contribute to chemical release. Repeated use and elevated temperatures were found to influence migration patterns, indicating changes in material stability over time. These findings provide new insights into the behaviour of TPU-based hydration systems under realistic conditions and highlight the importance of considering repeated-use scenarios when evaluating the suitability of polymeric materials for food and beverage contact applications.