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

Abstract

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.