Rapid Identification and Quantification of Microplastics in the Environment by Quantum Cascade Laser-Based Hyperspectral Infrared Chemical Imaging

The
monitoring of the emerging contaminant, microplastics, in the
environment, in water supply, and for food safety is of major interest
to science, consumers, and governments. While the chemical analysis
of these particles is considered mandatory, a rapid and reliable method
for the determination of particle sizes, shapes, and numbers is missing,
as existing methods are not fitting into current laboratory measurement
routines. In this study, we present an approach for circumventing
these issues through the application of quantum cascade laser-based
microscopy combined with an automated data analysis. This method allows
the measurement of an area of 144 mm2 in 36 min, with a
pixel resolution of 4.2 μm, which is an appropriate timeframe
and spatial resolution for routine measurements. The performance was
compared to the existing state-of-the-art Fourier transform infrared
microscopy analyses. Further, the application of the method on various
environmental samples was investigated to examine its capacity to
provide number and variety of present particles. The described analytical
procedure overcomes the last restrictions for schedulable and rapid
microplastic monitoring, resulting in a highly detailed data set for
particle numbers, particle shapes, and polymer types.