The problem with all formula finders is, that the number of formulae explodes in higher mass ranges (above 500 u) and sometimes several hundred thousand formulae are generated for a single accurate mass. One of the best free formula generators is theįormula Finder included in MWTWIN. There are many free and commercial formula generators.
RDBs are overloaded to maximum valence values (N=3,P=5,S=6).ġ9,308 formulas found in 1028 seconds by evaluating 50,533,733,862 formulae.ĭownload the free Seven Golden Rules software for elemental composition determination of small molecules here.
The Seven Golden Rules are currently limited to elements C, H, N, S, O, P, F, Cl, Br, Si (the most common elements) and also exclude salts and odd electron compounds (like nitroso compounds).Įxample output from HR2 (50 billion formulae evaluated - speed around 50 million formulas per second).ġ073 formulas found in 1 seconds by evaluating 82,826,316 formulae. Especially the further development of the brute-force formula calculator HR2 allows counting molecular formulas in certain mass range with very high speed (usually 10 million formulas per second on an Intel Core Duo 2.0 GHz or AMD Opteron 2.8 GHz). HiRes for calculating some these properties. presence of trimethylsilylated compounds.element ratio of nitrogen, oxygen, phosphor, and sulphur versus carbon,.restrictions for the number of elements,.
Molecular formula generator HR2 which is used for the Seven Golden Rules is a speed-enhanced version of HiRes MS (developed by Joerg Hau) can be downloaded As these rules must be universal (no cherry picking or magic “pre-knowledge” allowed) they were developed and confirmed using a large dataset of 750,000 formulae covering more than 10 million known and existing compounds (PubChem, Wiley, NIST, DNP, KEGG, Beilstein, CAS).
Seven Golden Rules use heuristic rules for limiting the number of formulas only to the most probable ones. Hence chemometric rules must be applied to constrict the number of molecular formulas. The main problem with all formula generators is: they produce too many wrong formula candidates and some of the generators are very slow. Usually a certain mass range (in ppm, in Da) must be entered to generate formulae in this range also elements which should be included and excluded must be named. Molecular Formula Generator generates possible elemental compositions from an given molecular mass.