In a simplistic sense, our current measurements for the chemical space rely on getting separated compounds into a mass spectrometer under conditions which are sufficient for them to be measured. This has heavily relied on the ability to easily introduce the chemicals into liquid (mainly RPLC) and gas chromatography and separation based on interactions between the chemicals, a solid phase and a mobile phase. This implies that the compounds are already in a liquid or gaseous solution hence already excludes particles, low solubility chemicals, and non-volatiles. Mass spectrometry requires chemicals to be in an gaseous ionized state and ionization has largely focused on soft ionization for LC (mainly electrospray (ESI) and atmospheric pressure chemical ionisation (APCI)) to produce psuedo-/molecular ions (precursor ions), and hard ionization (electron impact (EI)) for GC which typically fragments the molecules. As such, chemicals with poor ionization efficiency will likely not be 13 introduced to the mass spectrometer, and those which have very high ionization efficiency may fragment too much to provide sufficient identification of the parent compound. Even those which do ionize may be unstable or rearrange. Beyond ionization, precursors are typically fragmented using collision-induced dissociation also known as collisionally activated dissociation and then measured via tandem mass spectrometry. Only recently have we seen the introduction of electron-activated dissociation (EAD) into commercial mass spectrometers and as such new libraries need to be developed to identify chemicals based off the spectrum produced through EAD.