Abstract: Interfering Factors on ~(15)N Mass Spectrometric Analysis of Atmospheric NitrogenJin Deqiu; Wang Jianyao;Zhang Qinglian (T. L. Chang) (Department of Chemistry,Peking University,Beijing 100871,China) Abstract:Atmospheric nitrogen has been adopted as the reference material for natural ~15N abundance measurement, which is, however, interfered by the presence of oxygen and argon. Consequently an investigation was carried out with a VG SIRA-24 mass spectrometer. It was found that 21 % O_2 and 1%Ar (volume percent) change the δ~15N value by-0. 88‰ 0 and -0. 09‰ respectively.Keywords: atmospheric nitrogen, ~(15)N, mass spectrometric analysis,O_2,Ar