This Raman spectral library is designed for the identification of common and uncommon synthetic polymer microparticles and is suitable for all environmental sample types. Below are the reasons behind its structure:

Composition of the library
The library contains 30 spectra in total: 28 synthetic polymers and two minerals (carbonate and silicate). Only a single spectrum is included for each polymer type so as not to overload the library or increase spectral matching times unnecessarily.

Exclusion of pigmented plastics
The library does not contain coloured (pigment-containing) plastics because specific pigments exhibit unique Raman signals. Since the same pigments can be used across different polymer types, a pigment is not relevant to polymer identification and may lead to misclassification.

Guidance for Similarity-Based Searches (SBS)
When using the library in Similarity-Based Searches (SBS), spectral matches must be confirmed by a trained interpreter even if the hit-quality index (HQI) is high. HQIs are only referential and should be used as a primary sorting tool, not as a decisive measure of identification. We recommend setting a lower threshold below which polymers are excluded (e.g., 80%; depending on the polymer type) and above which spectral matches are manually evaluated by a trained interpreter.