Abstract: Gas Composition and Gas Isotope Analysis by Mass SpectrometryLi Liwu;Wen Qibing (Lanzhou institute of Geology,Chinese Academy of Sciences,Lanzhou 730000,China)Abstract:Mass spectrometry(MS)is the only method of choice for accurate,fast,and cost effective analysis of gas mixtures with very wide ranges of concentrations,and allowing very small sample capability.In this paper,some results of gas compositions and N,Ar isotopes obtained by MAT271 mass spectrometer are reported.Keywords:MS,composition,isotope