Discussion and Elimination of Interferences in Measurement of Isotopic Ratio of Noble Gases in Hydrocarbon Natural Gases

The measurement of the noble gas isotopes in hydrocarbon natural gases is relatively difficult because their content is very low.In order to reach the accurate values of noble gas isotopes,it is necessary to pay attention to eliminating a lot of interferences.According to work experiences and theoretical analysis,the author suggests that the main factors,interfering the accurate measure ments of the noble gas isotopes for specimens of hydrocarbon natural gases,include that:additional ion fragments,very large contents differences,wide isotope differences of noble gases in different samples.In addition,disturbances of the background of instrument system,leaks and the gas release from materials,etc.Should be also considered for isotopic analysis of noble gases.Furthermore,a series of useful methods are presented to eliminate the interferences and to control the disturbance.