Mass Spectrometry Adduct Calculator

We
describe the Mass Spectrometry Adduct Calculator (MSAC), an
automated Python tool to calculate the adduct ion masses of a parent
molecule. Here, adduct refers to a version of a parent molecule [M]
that is charged due to addition or loss of atoms and electrons resulting
in a charged ion, for example, [M + H]+. MSAC includes
a database of 147 potential adducts and adduct/neutral loss combinations
and their mass-to-charge ratios (m/z) as extracted from the NIST/EPA/NIH Mass Spectral Library (NIST17),
Global Natural Products Social Molecular Networking Public Spectral
Libraries (GNPS), and MassBank of North America (MoNA). The calculator
relies on user-selected subsets of the combined database to calculate
expected m/z for adducts of molecules
supplied as formulas. This tool is intended to help researchers create
identification libraries to collect evidence for the presence of molecules
in mass spectrometry data. While the included adduct database focuses
on adducts typically detected during liquid chromatography–mass
spectrometry analyses, users may supply their own lists of adducts
and charge states for calculating expected m/z. We also analyzed statistics on adducts from spectra contained
in the three selected mass spectral libraries. MSAC is freely available
at https://github.com/pnnl/MSAC.