Validation of ATR FT-IR to identify polymers of plastic marine debris, including those ingested by marine organisms
Melissa R. Jung, F. D. Horgen, Sara V. Orski, Viviana Rodriguez Cardenas, Kathryn L. Beers, George H. Balazs, T. T. Jones, Thierry M. Work, Kayla C. Brignac, Sarah-Jeanne Royer, K. D. Hyrenbach, Brenda A. Jensen, Jennifer M. Lynch
Polymer identification of plastic marine debris can help identify its sources, degradation, and fate. We optimized and validated a fast, simple, and accessible technique, attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), to identify polymers contained in plastic ingested by sea turtles. Spectra of consumer good items with known resin codes #1-6 and several #7 polymers were compared to those of scientifically-sourced and raw manufactured plastics. An inter-laboratory comparison with high temperature size exclusion chromatography confirmed ATR FT-IR could differentiate these polymers. High-density (HDPE) and low-density polyethylene (LDPE) discrimination is challenging but a clear step-by-step guide is provided that identified 78% of ingested PE samples. The optimal cleaning methods were wiping ingested pieces with water or cutting. Of 828 ingested plastics pieces from 50 Pacific sea turtles, 96% were identified by ATR FT-IR as HDPE, LDPE, unknown PE, polypropylene (PP), PE and PP mixtures, polystyrene, polyvinyl chloride, and nylon.