Fenthion is an organothiophosphate insecticide,which is a subset of the organophosphates.The analysis of impurities in the pesticide plays an important role in quality control,making a strong impact on the quality of preparation,crops,non-target organisms,human health and the ecological environment.In this article,fenthion and 7 impurities were separated by GC and HPLC,and identified by using electron impact mass spectrometry(EI MS) and electrospray ionization mass spectrometry(ESI MS) methods.The fragmentation reactions of fenthion were further investigated in order to speculate the fragmentation structures of
