SLoPP and SLoPP-E: Open Spectral Libraries for Microplastics Identification
Citation: Munno, K., De Frond, H., O’Donnell, B., & Rochman, C. M. (2020). Increasing the Accessibility for Characterizing Microplastics: Introducing New Application-Based and Spectral Libraries of Plastic Particles (SLoPP and SLoPP-E). Analytical Chemistry, 92(3), 2443-2451. DOI: 10.1021/acs.analchem.9b03626
Overview
The Spectral Library of Plastic Particles (SLoPP) and its companion SLoPP-E (Spectral Library of Plastic Particles – Environmental) are open-access Raman spectral databases created to improve and democratize microplastic identification. Developed by the Rochman Lab at the University of Toronto, these tools provide standardized spectral references for a broad range of polymers, colors, and morphologies—essential for confirming whether small particles are truly microplastics.
What These Tools Offer
- SLoPP contains 148 reference spectra from pristine consumer and laboratory plastics, spanning 12 polymer types (PE, PP, PET, PS, PVC, ABS, PMMA, PU, PA, PC, PVA, and acrylic) plus natural fibers such as cotton and cellulose acetate.
- SLoPP-E adds 113 spectra from environmentally aged plastics collected across diverse matrices and geographies, capturing the spectral changes caused by weathering, pigment loss, and surface oxidation.
- An application-based library provides recommended Raman settings (laser wavelength, filter %, acquisition time, grating, etc.) tailored to particle color, size, and morphology, helping researchers acquire clear spectra and minimize fluorescence interference.
Together, these resources boost the accuracy and reproducibility of Raman-based microplastic analyses and enhance comparability among studies.
Why It Matters
Raman spectroscopy is powerful for detecting small ( < 5 µm ) microplastics but often limited by incomplete or costly commercial spectral libraries. By offering open, validated reference spectra—including real-world, aged particles—SLoPP and SLoPP-E increase the likelihood of correct polymer identification. When used alongside commercial databases, 63 % of top-five matches in validation tests were derived from SLoPP and SLoPP-E, confirming their practical value for environmental and regulatory research.
Access and Use
Both libraries are freely available to the scientific community. Users can import them into Raman analysis platforms such as Bio-Rad KnowItAll and apply them for:
- Environmental and laboratory microplastic identification
- Training automated spectral matching or machine-learning classifiers
- Cross-validation of FTIR or Raman datasets
- Method development for emerging nanoplastic studies
Learn More
Explore the full paper and supporting datasets via the American Chemical Society (ACS) Analytical Chemistry journal:
https://pubs.acs.org/doi/10.1021/acs.analchem.9b03626
These resources are part of Plastiverse.org’s Open Microplastics Toolkit, advancing transparent, reproducible, and accessible science for tracking plastic pollution worldwide.
Keywords
microplastics spectral library, Raman spectroscopy, SLoPP, SLoPP-E, Rochman Lab, polymer identification, environmental microplastics, aged plastics, open-access spectra, FTIR vs Raman comparison, pigment interference, analytical chemistry, University of Toronto, standardized microplastic methods