The Mass Spectrometry Data Center (MSDC) has recently started improving existing libraries and creating new ones for identifying and analyzing plastics-related compounds (PRC) and materials (PRM) as part of the NIST circular economy program. PRC are small molecules of dissimilar chemical nature; hence, to increase coverage, we have used three types of ionizations: EI, ESI, and APCI. PRM are solids that include polymers, polymer mixtures, and commercial plastics, so we have used pyrolysis-gas chromatography (py-GC-MS) to create a new searchable library. First, we have increased the coverage of the existing libraries by including as many as possible commercially available PRC. Then, for testing the libraries and to deconvolute complex PRM mixtures, we have analyzed extractable and leachable (E&L) samples and pyrolysis products from one hundred standards of the most common polymers and some of their mixtures using LC-MS/MS, GC-MS, and py-GC-MS. In collaboration with the FDA, the EPA, and other non-government institutions, we are applying techniques, libraries, and tools to areas of interest to the circular economy of plastics, health risk assessments, and environmental challenges.