Characterization of microplastics on filter substrates based on hyperspectral imaging: Laboratory assessments

Optimization of a hyperspectral imaging system for rapid detection of microplastics down to 100 µm

“…4 c, right panel). The system was verified to be successful to detect 11 common polymer types in the household and industrial sectors and perspectives for quantitative evaluation of microplastic masses [20] . We expect that the modified hyperspectral imaging system could be applied to rapidly detect small microplastics collected on filter substrates.…”

“…The average dark current noise was first measured while the objective lens was blocked and then subtracted from all data to define zero reflectance. The signal was then scaled by measuring absolute reflectance (reflectance = 1) using a gold-coated polycarbonate filter (GPC0847-BA, Structure Probe, Inc., USA), which is an appropriate substrate for microplastic detection [ 20 ]. After adjusting the focus of the objective lens, the near-true aspect ratio was attained through adjustment of the scanning speed and the frame rate (line acquisition rate) considering the linear scan character of the system and conducted with the Spectronon Pro software.…”

“…Adopting the Spectral Angle Mapper classification [10] , PE particles were identified ( Fig. 4 a, right panel) using a reference PE spectrum obtained beforehand [20] . To obtain a smooth spectrum (average of 3 pixels or more), we suggest that the default system is only applicable to relatively large (>500 µm) microplastics.…”

Nanomechanical Atomic Force Microscopy to Probe Cellular Microplastics Uptake and Distribution

“…Microscopy observations are particularly important for evaluation of commercially-available submicron plastics (e.g., polystyrene nano- and microparticles) cellular uptake and biodistribution [ 15 ], which requires fluorescence labelling of polystyrene prior to ingestion by cells followed by fluorescence wide-field or confocal microscopy [ 16 , 17 ]. Pre-treatment or post-treatment with polymer-targeting fluorescent dyes is essential for visualisation of cellular uptake and intracellular distribution of commercial spherical polystyrene microbeads [ 18 ], whereas label-free techniques utilising infrared [ 19 , 20 ] or Raman [ 21 ] microspectroscopy are mostly reserved for diverse environmental samples, where the chemical composition of the particles analysed is unknown. Recently, label-free detection of polystyrene microplastics by means of reflected light hyperspectral microimaging [ 22 ] and dark-field microscopy along with neural networks [ 23 ] were developed for in vitro and in vivo applications.…”

Application of spectral features for separating homochromatic foreign matter from mixed congee

“…In addition to the analysis of the chemical composition of the sample, accurate spectral and spatial data should be acquired from the sample surface ( Zhang, Li, & Yang, 2017 ). HSI technology satisfies these requirements and has been successfully used to detect FM such as plastics, branches, and leaves in agricultural products ( Serranti et al, 2018 , Torres et al, 2019 , Zhang et al, 2016 , Zhu et al, 2020 ; ). Therefore, the spectral data of the entire mixed congee sample can be acquired pixel by pixel by using HSI technology to realize the recognition of homochromatic FM.…”