SERDP has implemented research to develop improved forensic methods and tools for source tracking and allocation of PFAS. Specifically, the goal is to evaluate conventional or novel analytical techniques or methodologies that differentiate PFAS coming from AFFF sources from those coming from non-AFFF sources. Additionally, the research will develop spectral libraries of PFAS that include both AFFF-derived PFAS and PFAS derived from other sources. Improved analytical methods and/or validated models will also assist with prediction of changes to AFFF mixtures over time, including chemical pathways to the most toxic compounds.