Method development for the determination of microplastic particles in marine samples using micro-FTIR - FPA spectroscopy

In the early 80s the environmental pollution with plastic was recognised and investigated (Scott, 1972). Meanwhile the problematic situation with plastic pollution is still discussed different media, like film documentations and newspapers. Actual reports enlarge those issues with worldwide screenings and show a contamination situation from beaches over the ocean surface to the oceanic sediment zone (Thiel et al., 2013; Moret-Ferguson et al., 2010). This is not only a visible aesthetic problem its further displayed that plastic can accumulate in the fauna which can have severe implications (Poppi et al., 2012) as plastic has been shown to adsorbed persistent organic pollutants (POP) (Engler, 2012). Regarding that, microplastic defined as plastic particles smaller than one millimetre can be addressed as a major impact factor for environmental pollution situations with plastic garbage. The small particles enter the marine environment directly as primary microplastics or originate as a result of the degradation of plastic litter from illegal dumping, accidental industrial spillages, sewerage overflows, or tourism (Barnes et al., 2009). This thesis addresses the development of a method for the detection of microplastic particles in marine environmental samples. The main aim was to distinguish different polymer types and their distribution in the sample. A full automatic and non-destructive Fourier-Transformation-Infrared-Spectroscopy (FTIR) technique, micro-FTIRspectroscopy, a common measurement tool in the plastic polymer industry (Harrison et al., 2012) was applied. The device used thereby is a FTIR measurement system combined with a microscope. Backbone of the technology is a focal plane array (FPA) detector. With this detector a huge number of spectra can be recorded within a short timespan of milliseconds. The special detector-design with its thousands of regularly located pixels, each understandable as single element detector, allows area resolved measurements. The study investigate the applicability of micro-IR-spectroscopy to examine marine environmental samples on the content of microplastic particles. It showed that filtration residues on special aluminium oxide filters in diameters up to 16 mm can be mapped to distinguish polymer types in the sample in spectral resolutions of at least 10.4 µm. The applied method allow a simultaneously differentiation between the most widespread industrial polymer types, e.g., polyethylene, polypropylene, polyvinylchloride, polystyrene, polyethylene terephthalate, polyamide, polycarbonate, polyester and polyurethane.