Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom; Department of Chemical Sciences, University of Padua, Via Marzolo 1, Padova, 35131, Italy.
Department of Chemical Sciences, University of Padua, Via Marzolo 1, Padova, 35131, Italy.
Chemosphere. 2019 Jun;224:786-795. doi: 10.1016/j.chemosphere.2019.02.151. Epub 2019 Feb 27.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous atmospheric pollutants of high concern for public health. In the atmosphere they undergo oxidation, mainly through reactions with ·OH and NOx to produce nitro- and oxygenated (oxy-) derivatives. In this study, we developed a new method for the detection of particle-bound PAHs, nitro-PAHs and oxy-PAHs using direct infusion into an atmospheric pressure photoionisation high-resolution mass spectrometer (APPI-HRMS). Method optimisation was done by testing different source temperatures, gas flow rates, mobile phases and dopants. Samples were extracted with methanol, concentrated by evaporation and directly infused in the APPI source after adding toluene as dopant. Acquisition was performed in both polarity modes. The method was applied to target analysis of seasonal PM samples from an urban background site in Padua (Italy), in the Po Valley, in which a series of PAHs, nitro- and oxy-PAHs were detected. APPI-HRMS was then used for non-target analysis of seasonal PM samples and results compared with nano-electrospray ionisation (nanoESI) HRMS. The results showed that, when samples were characterised by highly oxidised organic compounds, including S-containing compounds, like in summer samples, APPI did not bring any additional information with respect to nanoESI in negative polarity (nanoESI(-)). Conversely, for winter samples, APPI(-) could detect a series of aromatic and poly-aromatic compounds, mainly oxidised and nitrogenated aromatics, that were not otherwise detected with nanoESI.
多环芳烃（PAHs）是普遍存在的大气污染物，对公众健康高度关注。在大气中，它们会发生氧化，主要通过与·OH 和 NOx 的反应，生成硝基和含氧（氧）衍生物。在这项研究中，我们开发了一种使用大气压光电离高分辨率质谱仪（APPI-HRMS）直接注入检测颗粒结合态 PAHs、硝基-PAHs 和含氧-PAHs 的新方法。通过测试不同的源温度、气流速率、流动相和掺杂剂来进行方法优化。用甲醇提取样品，蒸发浓缩，然后在加入甲苯作为掺杂剂后直接注入 APPI 源。在正、负两种极性模式下进行采集。该方法应用于意大利波河谷帕多瓦市（意大利）城市背景点的季节性 PM 样品的靶向分析，在这些样品中检测到一系列 PAHs、硝基-PAHs 和含氧-PAHs。然后，APPI-HRMS 用于季节性 PM 样品的非靶向分析，并将结果与纳喷雾电离（nanoESI）HRMS 进行比较。结果表明，当样品中含有高度氧化的有机化合物，包括含硫化合物时，如在夏季样品中，APPI 在负极性（nanoESI(-))中与 nanoESI 相比没有提供任何额外信息。相反，对于冬季样品，APPI(-)可以检测到一系列芳香族和多环芳烃化合物，主要是氧化和氮化物芳香族化合物，而这些化合物用 nanoESI 无法检测到。
