The critical evaluation of a comprehensive mass spectral library

A description of the methods used to build a high quality, comprehensive re ference library of electron-ionization mass spectra is presented. Emphasis is placed on the most challenging part of this project-the improvement of q uality by expert evaluation. The methods employed for this task were develo ped over the course of a spectrum-by-spectrum review of a library containin g well over 100,000 spectra. Although the effectiveness of this quality imp rovement task depended critically on the expertise of the evaluators, a num ber of guidelines are discussed which were found to be effective in perform ing this onerous and often subjective task. A number of specific examples o f the particularly challenging task of spectrum editing are given. (C) 1999 American Society for Mass Spectrometry.