Hyperspectral imaging as an emerging tool to analyze microplastics: A systematic review and recommendations for future development

A central challenge in microplastics (MP, diameter < 5 mm) research is the analysis of small plastic particles in an efficient manner. This review focuses on the recent application of infrared hyperspectral imaging (HSI) to analyze MP. We provide a narrative context for understanding technical principles of HSI followed by a systematic review and discussion of the variety of approaches to apply HSI to MP research, including instrumentation, data collection and analysis. HSI was successfully applied to analyze dry MP > 250 μm, with drastic improvements in analysis time as compared with the best available technology, such as Fourier transform infrared (FT-IR) and Raman spectroscopy. Primary challenges we identified through the review include improving spatial resolution to detect smaller MP and development of robust models for data analysis. Parameters and practices for reporting quality assurance and quality control measures are summarized and recommendations are made for future research. We conclude that HSI is a promising technology for MP analysis but requires adaptation for this new application.