Fast Detection and Classification of Microplastics by a Wide-Field Fourier Transform Raman Microscope

A number of applications require methods to detect with high spatial resolution and chemical specificity microplastics (MPs) extracted from different matrices. Here we introduce a wide-field hyperspectral Fourier transform Raman microscope for the rapid detection and identification of MPs. The instrument, based on a common-path birefringent interferometer, combines high spatial (∼1 μm) and spectral (∼23 cm^-1) resolution with fast measurement times (∼15 min for a 100 kpixel image) and enables the suppression of sample fluorescence by a proper choice of the scan interval of the interferometer. After validating the instrument on MPs of commercial origin, we demonstrate its ability to detect MPs extracted from different matrices, by filtering seawater and pretreated gastrointestinal tracts of fish, and analyzing the MPs concentrated onto the filters. We expect that our microscope will enable high-quality, cost-effective, and rapid identification of MPs, fulfilling also the requirements of large-scale monitoring plans of different environmental matrices.