Formularity: Software for Automated Formula Assignment of Natural and Other Organic Matter from Ultrahigh-Resolution Mass Spectra

Ultrahigh
resolution mass spectrometry, such as Fourier transform
ion cyclotron resonance mass spectrometry (FT ICR MS), can resolve
thousands of molecular ions in complex organic matrices. A Compound
Identification Algorithm (CIA) was previously developed for automated
elemental formula assignment for natural organic matter (NOM). In
this work, we describe software Formularity with a user-friendly interface
for CIA function and newly developed search function Isotopic Pattern
Algorithm (IPA). While CIA assigns elemental formulas for compounds
containing C, H, O, N, S, and P, IPA is capable of assigning formulas
for compounds containing other elements. We used halogenated organic
compounds (HOC), a chemical class that is ubiquitous in nature as
well as anthropogenic systems, as an example to demonstrate the capability
of Formularity with IPA. A HOC standard mix was used to evaluate the
identification confidence of IPA. Tap water and HOC spike in Suwannee
River NOM were used to assess HOC identification in complex environmental
samples. Strategies for reconciliation of CIA and IPA assignments
were discussed. Software and sample databases with documentation are
freely available.