Automated Strategies To Identify Compounds on the Basis of GC/EI-MS and Calculated Properties

摘要

ABSTRACT: The identification of unknown compounds based on GCEI-MS spectrumand structure generation techniques has been improvednby combining a number of strategies into a programmed sequence. ThenprogramMOLGEN-MS is used to determine the molecular formula andnincorporate substructural information to generate all structures match-ning the mass spectral information. Mass spectral fragments are thennpredicted for each structure and compared with the experimentalnspectrum using a match value. Additional data are then calculatednautomatically for each candidate to allow exclusion of candidates that did not match other analytical information. The effectivenessnof these “exclusion criteria”, as well as the programming sequence, was tested using a case study of 29 isomers of formula C12H10O2.nThe default classifier precision resulted in the generation of too many structures in some cases, which was improved by up to severalnorders ofmagnitude by including additional classifiers or restrictions.Combining this with the exclusion of candidates based on a Leenretention index/boiling point correlation, octanol-water partitioning coefficients, steric energies, and finally spectral match valuesnlimited the number of candidate structures further from over 1 billion without any restrictions down to less than 6 structures in 10ncases and below 35 in all but 3 cases. This method can be used in the absence of matching database spectra and brings unknownnidentification based on MS interpretation and structure generation techniques a step closer to practical reality.