大气颗粒物中硝基多环芳烃的气相色谱-化学电离负离子-质谱联用法分析

MEASUREMENT OF PARTICULATE NITRATED POLYCYCLIC AROMATIC HYDROCARBONS USING GC-NCI/MS

比较了硝基多环芳烃(nitro-PAHs)的GC-EI/MS,GC-NCI/MS和HPLC-FLD分析方法,结果表明,GC-NCI/MS法选择性和灵敏度较高,样品前处理简单,满足大气颗粒物中痕量Nitro-PAHs的分析要求.用GC-NCI/MS法分析了厦门市钟鼓山隧道、厦门大学海洋楼和环岛干线大气颗粒物PM10中6种nitro-PAHs,包括9-硝基蒽(9-NAN)、2-硝基荧蒽+3-硝基荧蒽(2+3-NF)、1-硝基芘(1-NP)、7-硝基苯并[a]蒽(7-NBaA)和6-硝基苯并[a]芘(6-NBaP).结果显示,隧道样品中nitro-PAHs的浓度最高,6种nitro-PAHs的日均总浓度在1210.0—1931.0pg.m-3之间,其次为海洋楼顶和环岛干线,分别处于100.6—900.4pg.m-3和96.5—332.1pg.m-3范围内.隧道样品中1-硝基芘(1-NP)含量占绝对优势((60.9±7.0)%),显示汽车尾气直接排放的特征;而海洋楼顶和环岛干线站点的样品以2+3-硝基荧蒽(2+3-NF)为主,分别占到nitro-PAHs总浓度的(54.9±6.7)%和(66.4±5.0)%,说明受气相反应生成的影响明显.海洋楼顶PM10中nitro-PAHs的浓度显示明显的昼夜变化规律,夜间nitro-PAHs浓度及2+3-NF/1-NP比值均明显高于白天,说明大气颗粒物中的nitro-PAHs受光降解的影响明显,夜间nitro-PAHs主要由PAHs与NO3.自由基的反应生成.

The analysis methods of particulate nitrated polycyclic aromatic hydrocarbons（nitro-PAHs）were compared by gas chromatography-negative chemical ionization/mass spectrometry（GC-NCI/MS）,gas chromato-graphy-electron impact/mass spectrometry（GC-EI/MS）,high performance liguid chromatography-fluorescence detection（HPLC-FLD）.The result shows that the GC-NCI/MS method has higher selectivity and sensitivity than the other two methods and the pre-treatment process of samples before GC-NCI/MS analysis is simple.Six nitro-PAHs,including 9-nitroanthracene（9-NAN）,2＋3-nitrofluoranthene（2＋3-NF）,1-nitropyrene（1-NP）,7-nitrobenz[a]-anthracene（7-NBaA）and 6-nitrobenz[a]pyrene（6-NBaP）,were identified and quantified in PM10 samples collected inside Zhonggu tunnel,on the roof of Ocean building and a site close to Around-the-Island line in Xiamen in November 2008.The daily averaged concentrations of nitro-PAHs in the tunnel ranged from 1210.0 to 1931.0 pg·m-3 and 1-nitropyrene（1-NP）dominated the nitro-PAHs profile（（60.9±7.0）%）,suggesting the primary source was vehicle exhausts.The concentrations of nitro-PAHs measured at the site of Ocean building and Around-the-Island line ranged from 100.6 to 900.4 pg·m-3 and from 96.5 to 332.1 pg·m-3,respectively.The 2＋3-nitrofluoranthene（2＋3-NF）predominated the profiles at the above two sites（accounting for（54.9±6.7）% and（66.4±5.0）%,respectively）suggesting the importance of gas phase formation of nitro-PAHs and the rapid transformation rate of PAHs to nitro-PAHs.The significant diurnal variations of 6 nitro-PAHs concentrations and the ratios of 2＋3-NF to 1-NP measured on the roof of Ocean building highlighted the importance of the gas phase formation of nitro-PAHs from NO3·radical-initiated reactions during the night time and the importance of photo degradation in the daytime.