An online solid-phase extraction (SPE)-coupled liquid chromatography-mass spectrometry (LC-MS) method was established for the determination of 10 nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) in water. Water samples were mixed with methanol to generate 40% methanol solutions (v/v), and filtered by 0.45 μm membrane. The filtration with polytetrafluoroethylene(PTFE) membrane got higher recovery rates than nylon membrane, especially for 4-ring and 5-ring nitro-PAHs. 2.5 mL solution was directly injected into online SPE flow path to allow for online purification and enrichment of target analytes in the SPE column. The nitro-PAHs eluted from the SPE column were automatically transferred to the analytical flow path by a well-designed valve-switching system. With the optimization of LC and MS condition, ten nitro-PAH isomers was separated and detected from each other by LC-MS/MS with negative atmospheric pressure chemical ionization (APCI). It was firstly found that nitro-PAHs could produce strong [M-H]⁻ precursor ions in the primary MS besides [M+e]⁻ and [M+15]⁻. In the secondary MS, the precursor ions mainly lose NO neutral molecule (30 Daltons) to produce daughter ions. The online SPE and LC-MS analysis process was completed in 15.5 min. The linear correlation coefficients of 10 nitro-PAH standard curves were higher than 0.99. The detection limits of nitro-PAHs were about 1.2~22.2 ng/L (S/N=3). The intra-day and inter-day reproducibility (RSD, n=6) were 1.6%~8.4% and 5.3%~16.9%, respectively. The recoveries of 10, 40 and 200 ng/L in tap water were 71.7%~106.4%, 79.7%~100.9% and 73.0%~105.5%, with the corresponding RSD of 2.4%~10.5%, 2.1%~8.6% and 2.7%~6.2%, respectively.

建立了在线固相萃取-液相色谱-质谱联用法测定水中10种硝化多环芳烃（硝基-PAHs）的方法。将水样品与甲醇混合以生成40％甲醇溶液（v / v），并用0.45μm膜过滤。聚四氟乙烯（PTFE）膜的过滤回收率高于尼龙膜，特别是对于4环和5环硝基PAHs。将2.5 mL溶液直接注入在线SPE流路中，以在线纯化和富集SPE色谱柱中的目标分析物。通过精心设计的阀切换系统，将从SPE色谱柱洗脱的硝基PAHs自动转移到分析流路。通过优化LC和MS条件，分离了十种硝基-PAH异构体，并通过带有负大气压化学电离（APCI）的LC-MS / MS进行了检测。首次发现硝基PAHs可以产生强[MH]^-除了[M + e] ^-和[M + 15] ^-之外，初级质谱中的前体离子。在二次质谱中，前体离子主要失去NO中性分子（30道尔顿）而产生子离子。在线SPE和LC-MS分析过程在15.5分钟内完成。10条硝基-PAH标准曲线的线性相关系数均高于0.99。硝基多环芳烃的检出限约为1.2〜22.2 ng / L（S / N = 3）。日内和日间重现性（RSD，n = 6）分别为1.6％〜8.4％和5.3％〜16.9％。自来水中10、40和200 ng / L的回收率分别为71.7％〜106.4％，79.7％〜100.9％和73.0％〜105.5％，相应的RSD为2.4％〜10.5％，2.1％〜8.6％和分别为2.7％〜6.2％。