Plastic is a persistent and growing environmental pollutant. Small (largest crosswise dimension &lt;5 mm) particles called ‘microplastics’ (MPs) are of special concern because they have been found to disrupt marine ecosystems globally. The presence of MPs contaminating freshwater and terrestrial systems has also been reported. It has been assumed that marine contamination is mainly of terrestrial origin, but systematic studies of its sources are lacking. An absence of standardized characterization and monitoring methods has slowed the progress of understanding the sources, transport, and impact of MPs into the environment. In this study, stable carbon isotope ratio mass spectrometry (IRMS) and Fourier transform infrared (FTIR) spectroscopy were used as complementary methods to characterize common plastics. In IRMS, carbon isotopic ratios (13C/12C) for materials are expressed relative to the ratio of a standard, as δ13C values. This technique has previously been applied to determine the origin of organic matter in the environment. Based on preliminary results, IRMS seems to be a promising tool for MP analysis. The δ13C values for petroleum- and plant-derived materials reflected their sources, while recycled materials had values between these two. Dyes in the plastics did not appear to affect the δ13C results, an advantage over spectroscopic methods. Other advantages of IRMS for MP analyses are high sensitivity; fast, automated analyses; and low cost. Disadvantages relative to FTIR-based methods are that IRMS is not a confirmatory technique, and it is destructive.

Preliminary assessment of FTIR and IRMS for characterization of microplastics

2019 Spring National Meeting

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