Mass Spectrometric Cleavage Behavior of 14 Diphenyl Ether Herbicides
The characteristic fragment ions and cleavage patterns of 14 Diphenyl Ether Herbicides(DpEH)were comparatively studied by analyzing their mass spectra in EI source.The mass spectrometry fragmentation of DpEH usually followed the following pattern:(1)Hydrogen rearrangement or i-breakage occurs when the free radical is localized at the oxygen atom of Diphenyl Ether;(2)i-breakage occurs when the free radical is localized at the oxygen atom of nitro,resulting in the loss of NO2,or it can form an excited state upon heating,leading to α-breakage and the loss of NO;(3)The ions with positive charge and chlorine substituent in the benzene ring generate fragment ions at m/z[M-36]and m/z[M-35];(4)Others ions easily lose fluorine radical in trifluoromethyl groups or CO in carboxyl group.The identification and confirmation of DpEH in EI source can be achieved with the aid of characteristic fragment ions and cleavage patterns,providing a theoretical basis for quantitative and qualitative ion selection.
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