Synthesis of 14C-Labeled Polyethylene Terephthalate and Generation of 14C-Nanoparticles for Fate and Disposition Studies

Abstract

Polyethylene terephthalate (PET) is one of the most extensively used plastics in daily life. Due to its prevalent use, it is ubiquitous in the environment and a significant contributor to plastic pollution. Continuous exposure to photochemical, thermal, biological, and mechanical processes makes PET susceptible to slow degradation and the production of microsized and/or nanosized particles known as PET microplastic/nanoplastic (MP/NP). MP/NP are widely detected in the environment, including in drinking water and human food; consequently, knowledge gaps on the impacts of MP/NP in human food sources have gained global attention. A large knowledge gap is the bioaccumulation and fate of PET MP/NP in food animals. The application of carbon-14 labeled PET NP in food animals would provide a relatively straightforward approach to understanding the degree of PET absorption and its tissue distribution after absorption. Here, a simple, fast, and efficient synthetic method is described to produce [¹⁴C]-PET NP. The method comprises the polycondensation of terephthaloyl chloride and readily accessible [¹⁴C]-ethylene glycol followed by nanoprecipitation. The synthesized [¹⁴C]-PET and [¹⁴C]-PET NP were characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering spectroscopy, thermogravimetric analyzer (TGA), and UV-Vis spectroscopy.