基于激光质谱的大气环境污染源浓度检测方法

Detection method of atmospheric environmental pollution source concentration based on laser mass spectrometry

气相色谱法(GC)检测大气污染源浓度增强光子电离数量少、耗时长,导致污染浓度检测效率低,激光质谱法可实现光子向高激发态跃迁,提升检测精度与效率。该方法融合共振增强多光子电离(REMPI)与飞行时间质谱(TOP-MS),分子共振激发产生电离信号,离子经过排斥电场及加速电场的引导,驶入飞行时间质谱飞行区进入电子倍增器,此时激发光源为266 nm激光;激光质谱仪基于上述原理采集、探测污染源后,依据激光电离粒子信号强度与被测污染物浓度成正比的原理求取大气环境污染源浓度。实验表明,激光质谱法可同时有效检测多种大气污染气体浓度,检测污染源中NO2、CO浓度最大误差分别为0.04×10^-4 g/L、0.05×10^-4 g/L。

Traditional gas chromatography(GC)methods cannot enhance multiphoton ionization,and time-offlight mass spectrometry cannot be obtained.Therefore,based on laser mass spectrometry,the method combines resonance enhanced multiphoton ionization(REMPI)and time-of-flight mass spectrometry(TOP-MS).Molecular resonance excitation generates ionization signals.Ions are guided by repulsive electric field and accelerated electric field,then they are driven into the flight zone of time-of-flight mass spectrometry and enter the electron multiplier.The laser mass spectrometer uses a light source of 266 nm.After collecting and detecting pollution sources based on the above principles,the concentration of air pollution sources is calculated according to the principle that the signal intensity of laser ionized particles is proportional to the concentration of pollutants measured.The experimental results show that laser mass spectrometry can effectively detect the concentration of various air pollutants simultaneously.The maximum errors of NO2 and CO concentration in the pollutant sources are 0.04×10^-4g/L and 0.05×10^-4g/L,respectively.