Each compound that contains a (AH)(AH)(F)C-C(AH)F 2 group is considered a PFAS, where the AH groups could be hydrogen or any other atom and the bond between both aliphatic carbon atoms is a single bond. This definition is used in this present work as a straightforward structural definition as a compromise between definitions A and C. Definition C: Each compound that contains a (R 1 )(R 2 )(F)C-C(R 3 )F 2 group is considered a PFAS, where the R groups are any atom except hydrogen and the bond between both aliphatic carbon atoms is a single bond. This is a new, very recent EPA definition . This definition will lead to the least amount of PFAS molecules. The automated analysis of the increasing number of accessible scientific documents may provide input to fuel scientific studies to identify novel molecules with potentially desired or undesired properties. OC|processor 18 is a modular semantic annotation toolkit, based on Apache UIMA . It is designed to annotate different document types such as PDF, images, HTML, XML, MS Office and plain text documents. It uses a range of established dictionaries and ontologies as well as rule-based algorithms to annotate and index scientific named entities such as diseases, genes, species and chemistry. The properties of concept synonyms as well as the hierarchy of ontological concepts are taken into account to provide more accurate context sensitive annotation.