Structure Elucidation of Small Molecules with Mass Spectrometry

The Influence of Mass Accuracy and Accurate Isotopic Pattern on the Calculation of Elemental Compositions

Project Partner:
Tobias KindOliver Fiehn

Metabolomic database annotations via query of elemental compositions: Mass accuracy is insufficient even at less than 1 ppm. 
BMC Bioinformatics 2006, 7:234;  PDF:10.1186/1471-2105-7-234 (see left side)

*The graphic does not imply the LTQ-FT or Orbitrap have no accurate isotopic pattern (they have :-).

Provided project software:
New software is published in the Seven Golden Rules section.
The software and text here is published under the CC-by license.

1) List of all 1.6 million molecular formulas 0-500 Da (elements CHNSOP, LEWIS check, ground state chemistry)
[Download ZIP]
2) Upper limits of mass accuracy [ppm] for unique formula assignment (elements CHNSOP)
[Download ZIP]
3) Example script for formula filtering 
[Download ZIP]
4) Molecular formulas 150-900 Da with isotope profiles used for calculations 
[Download ZIP]
5) Results for 10, 5, 3, 1 and 0.1 ppm mass accuracy and 20%, 10%, 5%, 2% and 1% isotopic abundance accuracy
[Download ZIP]

Links to external software used in the project:

2) MWTWIN Molecular Weight Calculator and Formula Generator for Windows
3) MS EXCEL + Visual Basic
4) Mercury6 for calculation of isotopic pattern (Algorithm by Alan L. Rockwood, Programming by Steve Van Orden) newer code here or at web.
5) Borland C compiler (C++Builder )
6) Statistica Dataminer v7
7) Structure generators Molgen and Molgen-Online and Deterministic Structure Generator
8) Formula generator CHEFOG from Chemsoft provided within the chemedu package.