大气中二氧化氮在线监测仪器的研制  

Development of An Instrument for On-line Monitoring NO_(2)

作　　者：杨闻达 程鹏 张曼曼 虞小芳 李慧蓉 田智林 YANG Wen-Da;CHENG Peng;ZHANG Man-Man;YU Xiao-Fang;LI Hui-Rong;TIAN Zhi-Lin(Institute of Mass Spectrometry and Atmospheric Environment,Jinan University,Guangzhou 510632,China;Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution,Guangzhou 510632,China)

机构地区：[1]暨南大学质谱仪器与大气环境研究所,广州510632 [2]广东省大气污染在线源解析系统工程技术研究中心,广州510632

出　　处：《分析化学》2021年第3期350-358,共9页Chinese Journal of Analytical Chemistry

基　　金：广州市科技计划项目(No.201804010115);国家重点研发计划项目(No.2018YFC0213904)资助。

摘　　要：基于湿化学采样和长光程吸光光度法,搭建了一套大气二氧化氮(NO_(2))在线监测仪器。本仪器包含3个单元:外置采样单元、泵送单元和检测单元。外置采样单元由3个串联的螺旋管组成,避光恒温且无采样管,NO_(2)在其中被选择性吸收;泵送单元采用隔膜泵和蠕动泵,通过管路系统控制气体采样和溶液输送;检测单元包括LEDs光源,长光程流通池和光谱仪,对NO_(2)生成的偶氮染料进行定量。通过优化测量波长,提高了仪器的准确性和稳定性,改善了吸收液配方,降低了药品的消耗量,也降低了维护需求。仪器的吸收效率高(>99.5%)、检出限低(40 ng/m^(3))、响应时间较短(4 min),测量不确定度为±10%,测量范围广(40 ng/m^(3)~410μg/m^(3)),可用于背景环境大气和污染源的监测。干扰测试结果表明,大气中主要干扰物对仪器的影响可以忽略。与商业化的42i型氮氧化物分析仪(Thermo公司)的结果对比,线性拟合相关性系数R^(2)=0.98,两者测量结果相差仅约3%,显示了较高的准确性和可靠性。Based on wet chemical sampling and long path absorption photometry,an instrument for on-line monitoring atmospheric nitrogen dioxide was developed.The instrument contained three parts,including external sampling unit,transfer unit,and detection unit.The external sampling unit was composed of three spiral coils connected in series,in which NO_(2)was selectively absorbed.It was protected with thermal insulation and light shielding,and no inlet line was used.The transfer unit used a diaphragm pump and a peristaltic pump to control gas sampling and solution delivery through a pipeline system.The detection unit included a LEDs light source,a long path flow cell,and a spectrometer to quantify the azo dye generated by NO_(2).By optimizing the measurement wavelength,the accuracy and stability of the instrument were improved,and the absorption liquid formula was changed to reduce the maintenance requirement.The instrument had a high absorption efficiency(>99.5%),a low detection limit(40 ng/m^(3))at a response time of 4 min,and a measurement uncertainty of±10%.With a wide measurement range from 40 ng/m^(3)to 410μg/m 3,it could be used to monitor the background environment atmosphere and the pollution source.The interference test showed that the main interference species in the atmosphere had negligible influences on the instrument.Compared with the commercial nitrogen oxide analyzer(Thermo 42i),the coefficient of determination R^(2)reached 0.98,and the difference between the two measurement results was only 3%,showing high accuracy and reliability.

关 键 词：长光程吸收光谱仪 在线测量 二氧化氮 干扰 

分 类 号：X851[环境科学与工程—环境工程] O657.3[理学—分析化学]