A mass spectral library based on chemical ionization and collision-induced dissociation

A so-called CI–CID mass spectral library based on GC–CI-MS–MS, LC–TSP-MS–MS, LC–ESI-MS–MS and LC–APCI-MS–MS data has been created and evaluated. The main advantage of the CI–CID spectral library is the independence of the chemical ionization and/or collision-induced dissociation procedure and the system apparatus used. Comparison of MS–MS spectra from different ionization methods indicate that fragment ions most often have the same m/z values, although the ratios differ widely for many compounds. Therefore, depending on the signal intensity of the fragment ions the m/z values of intense specific ions are put in the library at 100% and less intense ions at 50%. The result is a spectrum with the same m/z values compared to the acquired spectra but with different ratios. At the moment the library has some hundreds of entries produced at five different laboratories. The spreadsheet program, used to interchange data between laboratories, has full functionality of browsing. Spectra are presented in bar graph format and in tabular form. All input data, instrument configurations, experimental conditions, etc., are displayed. Adding search masses of the (un)known compound, all hits (total number and names) show up. The results of an interlaboratory study show that the CI–CID spectrum library can be used by all users. Comparison of spectra generated by different GC– or LC–MS–MS triple quad mass spectrometers and ion trap MS–MS systems, turned out to be fully comparable.