The critical evaluation of a comprehensive mass spectral library

Abstract

A description of the methods used to build a high quality, comprehensive reference library of electron-ionization mass spectra is presented. Emphasis is placed on the most challenging part of this project--the improvement of quality by expert evaluation. The methods employed for this task were developed over the course of a spectrum-by-spectrum review of a library containing well over 100,000 spectra. Although the effectiveness of this quality improvement task depended critically on the expertise of the evaluators, a number of guidelines are discussed which were found to be effective in performing this onerous and often subjective task. A number of specific examples of the particularly challenging task of spectrum editing are given.

Biodegradation of three selected benzotriazoles in aquifer materials under aerobic and anaerobic conditions

“…Detailed instrumental conditions are given in Supporting Information (SI). The mass spectrum of each peak in the total ion chromatograms (TIC) of GC-MS in scan mode was deconvoluted, and peaks were assigned identities using automated mass spectral deconvolution and identification system (AMDIS) (National Institute of Standards and Technology, Gaithersburg, MD, USA), which is able to identify chemical structures, estimate molecular weight, and generate chemical formulas for compounds corresponding to the respective peaks (Ausloos et al, 1999;Pongsuwan et al, 2007).…”

Development and validation of a spectral library searching method for peptide identification from MS/MS

“…While this process occasionally involves manual or computer-assisted assignment of peaks in the mass spectra to possible fragments, a general and commonly practiced method of identification is by library searching [17][18][19]. In this approach, a spectral library is meticulously compiled from a large collection of experimentally observed mass spectra of known compounds.…”

Lipid mediator informatics-lipidomics: Novel pathways in mapping resolution

“…3 Although gas chromatographymass spectrometry (GC-MS) can be used in many cases for identifi cation of structures, the required high column temperatures limit its use because many of the PUFA-derived LMs are thermo-labile. 13 In this context, search algorithms for GC-MS electron-impact-ionization spectra have been well studied, [14][15][16] as have those for both GC-MS chromatograms and mass spectra. 17 The contrast angle (or dot product, the cosine of the contrast angle) algorithm is widely used.…”

“…15 , 16 The dot product algorithm in MassFrontier uses the intensities of all peaks in MS/MS as a vector for computation and is not concerned with the identities of ions, whether they are molecular ions, ions derived from molecular ions, or ions from interfering substances in the samples. [14][15][16][17] Using the ions generated from interfering background can decrease the percent correct for best match of the search. Even the ions generated from unknown LMs contribute differently to the identifi cation.…”