12 January 2012, 16:15
Ernst-Abbe-Platz 2, seminar room 3423

Wiley Registry of Tandem Mass Spectral Data

Assoc. Prof. Dr. Herbert Oberacher (Institute of Legal Medicine, Innsbruck Medical University, Innsbruck, Austria)The ‘Wiley Registry of Tandem Mass Spectral Data’ represents one of the few tandem mass spectrometric libraries available for the identification of small bioorganic molecules that can be rated accurate, robust and transferable. In this talk, important aspects of library development (i.e. library design, functional principles of the search algorithm) will be discussed and performance parameters presented.

At the current stage of development, the library contains more than 12,000 spectra corresponding to more than 1,200 reference compounds. Compound-specific reference spectra were collected on a high-resolution quadrupole-quadrupole-time of flight instrument. Typically ten different collision energies were applied for fragmentation to ensure comprehensive coverage of compound-specific breakdown curves.

The tailor-made search algorithm is capable to handle tandem mass spectral libraries that contain multiple spectra per compound acquired at different collision energy values. During library search the similarity between a measured spectrum and each set of compound-specific reference spectra is determined, and a numerical value is provided as output that can be used to classify a match as correct or false positive. The search algorithm exhibits a high tolerance towards changes within the intensity distribution of different fragmentation pathways.

The performance of the library was evaluated with sample sets acquired in different laboratories using various instrumental setups. Statistical evaluation of the accuracy of identification revealed that sensitivity was typically > 95%. Of particular importance was the fact that almost no performance difference was observed for spectra acquired on different instruments. Thus, the library can be rated accurate, robust and transferable.