Electron impact fragmentations of chlorinated organophosphorus pesticides

Mass spectral fragmentations of six chlorinated organophosphorus pesticides were investigated using electron impact mass spectrometry. Understanding t he fragmentation pathways, based on the fragment ions of mass spectra, shou ld be useful in the structural elucidation and chemical identification of t hese compounds. The proposed fragmentation pathways were verified by collis ion-induced dissociation B/E-linked scan spectra. In most cases, the struct ures of characteristic fragment ions could be expected by the observation o f the peak clusters due to Cl-35 and Cl-37 isotopes. According to substitut ed groups on phosphorus atom, phosphate and phosphorothioate exhibited sign ificantly different fragmentation patterns. Especially, phosphate and phosp horothioate with diethyl ester produced more diverse fragment ions than tha t with dimethyl ester.