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Open Specy 1.0: Automated (Hyper)spectroscopy for Microplastics

Analytical Chemistry 2025 8 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Win Cowger, Aleksandra Karapetrova, Aleksandra Karapetrova, Clarissa Lincoln, Ali Chamas, Hannah Sherrod, Nicholas Leong, Katherine S. Lasdin, Christine M. Knauss, Vesna Teofilović, Monica M. Arienzo, Zacharias Steinmetz, Sebastian Primpke, Lindsay E. Darjany, Clare Murphy-Hagan, Shelly Moore, Charles J. Moore, Gwen Lattin, Andrew B. Gray, Rachel Kozloski, Jeremiah Bryksa, Benjamin Maurer

Summary

Researchers released Open Specy 1.0, an updated open-source software tool for automated spectroscopic analysis of microplastics, featuring new algorithms for batch processing and hyperspectral image analysis. The tool includes a library of over 40,000 Raman and FTIR reference spectra and two machine learning classifiers for polymer identification. The study demonstrates that this freely available tool can significantly reduce the time required for microplastic spectral analysis, which traditionally takes days per sample.

Microplastic spectral analysis is one of the most time-consuming processes in studying microplastic pollution, often requiring days per sample. Researchers are transitioning to automated batch and hyperspectral image analysis techniques to enhance efficiency. Open Specy, initially aimed at manual single-spectrum analysis, has now integrated automated methods. This updated version, Open Specy 1.0, introduces several new features, including two algorithms for automated processing (smoothing and particle compression), an extensive library containing over 40,000 open-source Raman and FTIR spectra, and two machine learning classifiers (logistic regression and k medoids) developed from this library. Furthermore, it includes a revamped user interface, an R package, and a benchmark data set for testing future advancements in automated techniques. Researchers evaluated various configurations for hyperspectral smoothing, particle identification, compression, and splitting, to achieve combined recovery rates between 50 and 150% particle counts, identities, and sizes with a coefficient of variation (CV) of less than 40% (the accredited standard). Mean absorbance times the standard deviation provided a consistent particle identification. Hyperspectral smoothing led to a 96% combined recovery rate and reduced variability (CV = 38%) compared to the 86% recovery (CV = 83%) of nonsmoothed controls. Additionally, compressing spectra for particles was significantly faster (>3×) and showed similar accuracy but with reduced variability than processing each pixel individually. Key challenges persist in automating spectral analysis, particularly in refining particle splitting algorithms, and improving identification routines to minimize false positives and negatives. New methods in sample preparation for better stabilization and dispersion of particles could overcome some of these issues.

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