The chemical molecular formula used in this experiment for the perovskite ceramics with (Na, K, Ba) complex A-sites and (Nb, Zr, Ti) complex B-sites is 0.98(Na0.5K0.5)NbO3-0.02Ba(Zr0.52Ti0.48) ceramics.
We note the molecular formula used to calculate the theoretical mass of modified ToyJ is that of the neutral molecule wherein three protons have been removed to accommodate the charge of the trivalent cobalt atom.
Common approaches first compute candidate molecular formulas using a set of potential elements.
Here, both the intensities and masses of the isotope pattern are used to score candidate molecular formulas using Bayesian statistics: The authors estimate the likelihood of a particular molecular formula to produce the observed data.
The table contains the m/ z RT information, intensity, and the accurate mass, which allows a quick analysis of putative molecular formulas using SmartFormula.
Table S1 of this file presents an example of molecular formulae used with counts of generated structures and Figure S1 gives a structure generation software screenshot.
Feeding this software with various molecular formulae allowed us to gather as many non-equivalent structures as necessary (for an example of molecular formulae used with counts of generated structures, and a structure generation software screenshot, see Additional file 1: Table S1 and Additional file 1: Figure S1).
Some software packages for molecular formula identification using isotope patterns are summarized in Table 1.
In total 473 spectra (319 [M + H]and 154 [M − H] were evaluated with MetFrag2010 using ChemSpider, as well as MetFrag2.2 using either PubChem or ChemSpider. The correct molecular formula was used to retrieve candidates. The results, given in Table 1, show the clear improvement between MetFrag2010 (73 Top 1 ranks with ChemSpider) and MetFrag2.2 (105 top 1 ranks with ChemSpider).
Enumerating all possible isomers allows us to overcome the boundaries of database searching: Simply generate all molecular structures corresponding to the parent mass or molecular formula, and use the output of the structure generator as a "private database".
