CASMI 2013: Identification of Small Molecules by Tandem Mass Spectrometry Combined with Database and Literature Mining.

The Critical Assessment of Small Molecule Identification (CASMI) contest was initiated in 2012 to evaluate manual and automated strategies for the identification of small molecules from raw mass spectrometric data. The authors participated in both category 1 (molecular formula determination) and category 2 (molecular structure determination) of the second annual CASMI contest (CASMI 2013) using slow but effective manual methods. The provided high resolution mass spectrometric data were interpreted manually using a combination of molecular formula calculators, fragment and neutral loss analysis, literature consultation, manual database searches, deductive logic, and experience. The authors submitted correct formulas as lead candidates for 16 of 16 challenges and submitted correct structure solutions as lead candidates for 14 of 16 challenges. One structure submission (Challenge 3) was very close but not exact (N (2)-acetylglutaminylisoleucinamide instead of the correct N (2)-acetylglutaminylleucinamide). A solution for one (Challenge 13) was not submitted due to an inability to reconcile the provided fragmentation pattern with any known structures with the provided molecular composition.