Abstract: Study on Conformation of Testosterone and Epitestosterone by Reaction Mass SpectrometryGuo Zhifeng;An Qiurong;Liu Pengyan;Jln Boil(Physical and Chemical Analysis Centre,Hebei University,Baodin 071002,China)Received Abstract:In the presenrt paper,testosterone and epitestosterone have been studied by reaction mass spectromrtry(RMS) using N-methyl-N-trinmethylsilytrifluoroacetamide(MSTFA)and trimethylchorosilane(TMCS) as reagent.In mass spectra the expected characteristic ionsM＋Si(me)3-Hhas been observedThe defference of the conformation between the both of them can be easily distinguished from the ratio of abundance of the molecular ion M+ and chareteristic ionM＋Si(me)3-H+Keywords:testosterone,epitestosterone,conformation,ion-molecrle reaction,RMS．