Determination of the Structure of Alkyl Radicals in a Series of Highly Toxic Organophosphorus Compounds Using Mass Spectrometry Databases and Library Search

We propose an approach to the identification of alkyl radicals attached to the ester oxygen atom in a series of highly toxic organophosphorus compounds, based on the revealed regularities in the formation of mass spectra of monofunctional RX compounds (R is alkyl radical and X is functional group). The method includes the extraction of the hydrocarbon subspectrum from the mass spectrum of the analyte and its comparison with the hydrocarbon subspectra of the known monofunctional compounds. Alkyl radicals are identified using simple metrics that characterize the coincidence of hydrocarbon subspectra. The results of the identification of alkyl (cycloalkyl) radicals in a series of O-alkyl (cycloalkyl) alkylphosphonofluoridates, and O-alkyl (cycloalkyl) N,N-dialkylphosphoramidocyanidates show that ≥95% of the structures of the radicals of these compounds are within 10 positions of the search result list.