FormulaM

Molecular formula enumeration from observed mass spectrometry $m/z$ values.

Overview

This pnpm workspace contains the Vite + TypeScript + Svelte front-end-only FormulaM app in apps/web/ and its validated scientific source data in packages/mass-data/. The app applies a simplified bare-ion exact-mass rule:

ion_mass = candidate_formula_mass - charge * electron_mass
candidate_mz = ion_mass / abs(charge)

The input mass is always observed $m/z$. Charge is required and explicit. FormulaM applies only the bare-ion electron-mass correction for charged species such as $\ce{[M]+}$, $\ce{[M]-}$, $\ce{[M]^2+}$, and $\ce{[M]^2-}$; it does not add adduct support.

Local development

Workspace scripts are defined in package.json, and the Web package scripts and dependencies are defined in apps/web/package.json.

pnpm install
pnpm run dev

The production build is written to apps/web/dist/.

Checks

The full automated check order is defined in .github/workflows/test.yml.

Run pnpm run validate:data for the focused mass-data integrity suite.

Scientific disclaimer

FormulaM enumerates candidate formulae from exact-mass constraints. A returned formula is not a confirmed molecular identity or structure. Confirm candidates with isotope-pattern agreement, MS/MS fragmentation, retention time, ionization behavior, sample context, and chemical plausibility.