A high accuracy method for Xenon isotope abundance measurements was developed on a Helix MC Plus static gas mass spectrometer，in order to solve the problem that the mass difference of the nine stable isotopes of Xe is large (about 9.6%) and the mass spectrometry detector is difficult to accept, for get the abundance of all the stable isotopes of Xe quickly and accurately. The gas sample containing Xenon was purified and separated before introduced into the mass spectrometer analyzing chamber firstly, which helps reducing the influence on Xenon isotopic measurement brought by other noble gases and active components. Then, a measurement method combining peak hopping and multi reception was used to achieve high precision measurement of all stable isotopes of Xe at extremely small sample amount based on the Helix MC Plus static gas mass spectrometer. The measured data were corrected by referring to the Xenon isotopic reference gas finally. Results show that, under the condition of small sample amount (approximately 1.12×10-12 mol), the relative standard deviation (RSD) of the measured 129Xe/132Xe, 130Xe/132Xe, 131Xe/132Xe, 134Xe/132Xe, 136Xe/132Xe were within 0.24% by Faraday, and 124Xe/132Xe, 126Xe/132Xe were within 0.22% and 0.39% by counting method separately. This method achieves abundance ratio analysis of trace Xe stable isotopes with good stability and high accuracy.

Xenon（Xe） isotopes from nuclear test and accidents are important monitoring components of the comprehensive nuclear test ban treaty（CTBT）.An approach for the reproducible and accurate compositional analysis of Xe isotope ratios by multiple collector inductively coupled plasma mass spectrometry（MC-ICP-MS） was described in this paper.A Xe enrichment and purification platform was established to separate Xe from the collected atmosphere gas,enriching the Xe concentration and utilizing high purity argon as aerosol carrier,thus resulting in eliminating the negative influences of organic compound and particles on mass spectrometry.A relible Xe injection system was built to control the gas flow rate between the sample and the MC-ICP-MS in order to improve the stability and reproducibility of the ion-signals.Furthermore,several measures,including adsorbing Xe from the sample gas for mass spectrometry and baking the Xe introduction device for 2 hours with vaccum pumping,were taken to reduce the Xe blank.As a result,the blank signal of 129 Xe falled from 3.0 × 10 -2 V to 2.7 × 10 -3 V.Analyses were performed on a Neptune XT MC-ICP-MS,and standard sample bracketing（SSB） was involved in correcting the mass fractionation.The approach was successfully validated by the measurement of standard reference materials in 24 hours,showing that the relative uncertainties for all Xe isotope ratios were less than 0.09%（n = 7）,while the results agreed with the certificated values within uncertainty range.Especially,the relative uncertainties for 130 Xe/ 131 Xe and 132 Xe/ 131 Xe ratios were 0.007 1% and 0.006 9%,respectively.Two kinds of atmosphere gas collected at different times were analyzed and distinguished successfully by the proposed approcach.The results demonstrated that the developed technique was a precise and accurate method for Xe isotope dectection,Xe monitoring event identification and event sourcing.