between spectra of a set. When applied to a reference set of spectra for Type I fentanyl
analogs (molecules differing from fentanyl by a single modification), the map illuminates
clustering that is applicable to automated structure assignment of unidentified molecules. An
open-source software implementation that generates mass spectral similarity mappings of
unknowns against a library of Type I fentanyl analog spectra is available at http://github …