Microplastic constituent identification from admixtures by Fourier-transform infrared (FTIR) spectroscopy: The use of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and nylon (NY) as the model constituents

The ubiquity of microplastics receives an increasing concern due to their threats to the environment and ecology. The environmental sample of microplastics usually consists of a variety of polymer constituents, and the identification of each constituent is critical for pollution control and risk management. While the ambient microplastics were often analyzed considering the collected sample as a whole by measuring its weight and particle number, this study employed Fourier-transform infrared (FTIR) spectroscopy to identify the constituents of the tested microplastic admixture containing polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and nylon (NY). For each tested microplastic, the characteristic wave number(s) was determined based on its FTIR spectrum. Synthetic admixtures containing various combinations of tested microplastic constituents were analyzed, and the FTIR spectra enabled the identification of their respective plastic constituents. A procedure for microplastic identification was proposed. Additionally, samples from a selected industry and collected from the ambient environment were employed to explore the applicability of the proposed identification procedure. This study is a pioneer demonstration using FTIR to identify the microplastic constituents of an environmental sample