Figure 6:

2D-HQI of different microplastic particles from simultaneous O-PTIR and Raman acquisition with reference spectra. HQI of transparent, irregular-shaped PS (x), transparent PS beads (6 µm) (o) and colored PS beads (10 µm) (o) (a); irregular-shaped PC (b); and irregular-shaped PP (c). Black dots: putative contaminations with both low O-PTIR and Raman HQI.