PRODUCT-ION ASSISTED LIBRARY SEARCH OF THE ELECTRON IONIZATION MASS-SPECTRUM OF A MIXTURE

It has been found that fragment-ion spectra derived from molecular ion s do not, in general, achieve good scores when matched against standar d library mass spectra. Although the same m/z values may be observed, the relative intensities are frequently too different from those in th e EI mass spectral libraries. A strategy has been developed for compou nd identification in simple mixtures, in which fragment-ion spectra of molecular ions are adjusted to match the relative intensities of the same m/z values in the EI mass spectrum of the mixture. It is shown th at this simple adjustment permits more reliable identification of comp ounds in a mixture by library matching than does use of the unadjusted fragment-ion spectra.