Why are nH -perfluoroalkanoate ions more mobile than expected? Implications for identifying an emerging environmental pollutant.

nH -Perfluoroalkyl carboxylic acids ( nH -PFCAs) are emerging pollutants. Their identification by ion mobility is frustrated by the nH -PFCAs having unexpectedly small collision cross sections (CCS). Theory and experiment agree that this is because nH -PFCA ions undergo internal hydrogen bridging, and this insight will help guide the creation of more accurate methods for pollutant identification.