气相色谱-质谱联用法在线观测大气中的三氟化氮(NF_3)

In-situ measurement of atmospheric nitrogen trifluoride (NF_3) using GC-MS method

基于气相色谱-质谱联用技术(GC-MS)以及自制吸附解析装置,研发了一套大气中三氟化氮(NF_3)的自动在线监测系统,测试结果表明,系统精度3.9%(1σ),准确度1.2%,检出限0.23×10^(-12),表明该系统适用于大气中NF_3浓度在线观测.2016年9月—2017年5月在北京上甸子本底站进行了在线观测实验,空气样品时间分辨率130 min,获得大气中NF_3的本底和非本底浓度.本底数据百分比53.1%,平均本底浓度为1.72×10^(-12),与同纬度带的爱尔兰Mace Head站和美国Trinidad Head站浓度相当.非本底浓度的中位数2.41×10^(-12),相对平均本底浓度抬升40.1%.

Based on gas chromatography-mass spectrometry（GC-MS）and a custom-made sample prepartion unit,an in-situ system was developed for atmospheric nitrogen trifluoride（NF_3）measurement.Precision,accuracy and detection limit were 3.9%（1σ）,1.2%and 0.23×10^（-12）,respectively,which indicate the system could be used for in-situ measurement of atmospheric NF3.Field in-situ measurement was conducted during September 2016 to May 2017 at the Shangdianzi Background Station with a time resolution of 130 minutes for air samples.Both background and pollution samples were captured.Using the pollution filter,53.1%samples were selected as background data with an average mixing ratio of the 1.72×10^（-12）,consistent with the background level observed at Mace Head,Ireland and Trinidad Head,USA located at the similar latitude,while the median mixing ratio of polluted samples was 2.41×10^（-12）,which was 40.1%higher compared to the average background mixing ratio.