China National Environmental Monitoring Centre, Beijing, 100012, China.
China National Environmental Monitoring Centre, Beijing, 100012, China.
J Chromatogr A. 2021 Jan 4;1635:461738. doi: 10.1016/j.chroma.2020.461738. Epub 2020 Nov 19.
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 1.222.2 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.
建立了一种在线固相萃取（SPE）-液相色谱-质谱（LC-MS）方法，用于测定水中的 10 种硝基多环芳烃（硝基-PAHs）。水样与甲醇混合生成 40%甲醇溶液（v/v），并用 0.45μm 膜过滤。与尼龙膜相比，聚四氟乙烯（PTFE）膜的过滤效果更好，尤其是对 4 环和 5 环硝基-PAHs。将 2.5mL 溶液直接注入在线 SPE 流路，允许目标分析物在 SPE 柱中进行在线净化和富集。通过设计良好的阀切换系统，将从 SPE 柱洗脱的硝基-PAHs自动转移到分析流路。通过 LC-MS/MS 采用负大气压化学电离（APCI），对 10 种硝基-PAH 异构体进行了分离和检测。首次发现，除了[M+e]和[M+15]外，硝基-PAH 在主 MS 中还可以产生强[M-H]前体离子。在二级 MS 中，前体离子主要通过失去 NO 中性分子（30 道尔顿）来产生子离子。在线 SPE 和 LC-MS 分析过程在 15.5 分钟内完成。10 种硝基-PAH 标准曲线的线性相关系数均高于 0.99。硝基-PAH 的检测限约为 1.222.2ng/L（S/N=3）。日内和日间重复性（n=6）分别为 1.6%8.4%和 5.3%16.9%。自来水中 10、40 和 200ng/L 的回收率分别为 71.7%106.4%、79.7%100.9%和 73.0%105.5%，相应的相对标准偏差为 2.4%10.5%、2.1%8.6%和 2.7%~6.2%。
