University of North Dakota, Department of Chemistry, Grand Forks, ND 58202, USA.
Anal Chim Acta. 2012 Aug 31;740:93-103. doi: 10.1016/j.aca.2012.05.050. Epub 2012 Jun 5.
A sensitive method has been developed for the trace analysis of PAHs and their oxidation products (i.e., nitro-, oxy-, and hydroxy-PAHs) in air particulate matter (PM). Following PM extraction, PAHs, nitro-, oxy-, and hydroxy-PAHs were fractionated using solid phase extraction (SPE) based on their polarities. Gas chromatography-mass spectrometry (GC-MS) conditions were optimized, addressing injection (i.e., splitless time), negative-ion chemical ionization (NICI) parameters, i.e., source temperature and methane flow rate, and MS scanning conditions. Each class of PAH oxidation products was then analyzed using the sample preparation and appropriate ionization conditions (e.g., nitro-PAHs exhibited the greatest sensitivity when analyzed with NICI-MS while hydroxy-PAHs required chemical derivatization prior to GC-MS analysis). The analyses were performed in selected-ion-total-ion (SITI) mode, combining the increased sensitivity of selected-ion monitoring (SIM) with the identification advantages of total-ion current (TIC). The instrumental LODs determined were 6-34 pg for PAHs, 5-36 pg for oxy-PAHs, and 1-21 pg for derivatized hydroxy-PAHs using electron ionization (GC-EI-MS). NICI-MS was found to be a useful tool for confirming the tentative identification of oxy-PAHs. For nitro-PAHs, LODs were 1-10 pg using negative-ion chemical ionization (GC-NICI-MS). The developed method was successfully applied to two types of real-world PM samples, diesel exhaust standard reference material (SRM 2975) and wood smoke PM.
已开发出一种灵敏的方法，用于分析空气中颗粒物（PM）中多环芳烃及其氧化产物（即硝基、氧基和羟基多环芳烃）的痕量。在 PM 提取后，根据极性使用固相萃取（SPE）对多环芳烃、硝基、氧基和羟基多环芳烃进行分离。优化了气相色谱-质谱（GC-MS）条件，包括进样（即不分流时间）、负离子化学电离（NICI）参数，即源温度和甲烷流速，以及 MS 扫描条件。然后，使用样品制备和适当的电离条件（例如，硝基多环芳烃在 NICI-MS 分析时表现出最大的灵敏度，而羟基多环芳烃在进行 GC-MS 分析前需要化学衍生化）分析每种多环芳烃氧化产物。分析采用选择离子总离子（SITI）模式，将选择离子监测（SIM）的灵敏度提高与总离子电流（TIC）的识别优势相结合。使用电子电离（GC-EI-MS）确定的仪器检出限（LOD）分别为多环芳烃 6-34 pg、氧基多环芳烃 5-36 pg 和衍生羟基多环芳烃 1-21 pg。发现 NICI-MS 是确认氧基多环芳烃暂定鉴定的有用工具。对于硝基多环芳烃，使用负离子化学电离（GC-NICI-MS）的 LOD 为 1-10 pg。所开发的方法成功应用于两种实际 PM 样品，即柴油机排气标准参考物质（SRM 2975）和木烟 PM。
