Abstract: Study on Mass Spectrometry of Derivatives of CoumainJi Xiaoshen(Beijing Institute of Pharmaceutical Chemistry,PLA,Beijing 102205,China)Wang Xuefeng(The National Institute of Pharmaceutical Research and Development,Beijing 100083,China)Received Abstract:The mass spectra fragmentation patterns of 7-Hydroxy(Methoxy,Acetoxy)-3phenylcoumarin are reported.It is because of replacement of 3-phenyl that molecure shows high degree of conjugation.Therefore,the molecuir ions are the base peak when 7-position is hydroxy or methoxy group and M-CH3CO fragment ion is the base peak when 7-position is CH3COO.Keywords:coumarin,derivative,mass spectrum