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首页> 外文期刊>Analytica chimica acta >Optimisation of supercritical fluid extraction of polycyclic aromatic hydrocarbons and their nitrated derivatives adsorbed on highly sorptive diesel particulate matter
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Optimisation of supercritical fluid extraction of polycyclic aromatic hydrocarbons and their nitrated derivatives adsorbed on highly sorptive diesel particulate matter

机译：超临界流体吸附高吸附性柴油机颗粒物吸附多环芳烃及其硝化衍生物的工艺优化

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Supercritical fluid extraction (SFE) was performed to extract complex mixtures of polycyclic aromatic hydrocarbons (PAHs), nitrated derivatives (nitroPAHs) and heavy n-alkanes from spiked soot particulates that resulted from the incomplete combustion of diesel oils. This polluted material, resulting from combustion in a light diesel engine and collected at high temperature inside the particulate filter placed just after the engine, was particularly resistant to conventional extraction techniques, such as soxhlet extraction, and had an extraction behaviour that differed markedly from certified reference materials (SRM 1650). A factorial experimental design was performed, simultaneously modelling the influence of four SFE experimental factors on the recovery yields, i.e.: the temperature and the pressure of the supercritical fluid, the nature and the percentage of the organic modifier added to CO2 (chloroform, tetrahydrofuran, methylene chloride), as a means to reach the optimal extraction yields for all the studied target pollutants. The results of modelling showed that the supercritical fluid pressure had to be kept at its maximum level (30 MPa) and the temperature had to be kept relatively low (75 °C). Under these operating conditions, adding 15% of methylene chloride to the CO2 permitted quantitative extraction of not only light PAHs and their nitrated derivatives, but also heavy n-alkanes from the spiked soots. However, heavy polyaromat-ics were not quantitatively extracted from the refractory carbonaceous solid surface. As such, original organic modifiers were tested, including pyridine, which, as a strong electron donor cosolvent (15% into CO2), was the most successful. The addition of diethylamine to pyridine, which enhanced the electron donor character of the cosolvent, even increased the extraction yields of the heaviest PAHs, leading to a quantitative extraction of all PAHs (more than 79%) from the diesel particulate matter, with detection limits ranging from 0.5 to 7.8 ng for 100 mg of spiked material. Concerning the nitrated PAHs, a small addition of acetic acid into pyridine, as cosolvents, gave the best results, leading to fair extraction yields (approximately 60%), with detection limits ranging from 18 to 420 ng.
机译：进行超临界流体萃取（SFE），以从由于柴油未完全燃烧而产生的烟灰颗粒中提取多环芳烃（PAH），硝化衍生物（nitroPAHs）和重正烷烃的复杂混合物。这种污染物质是由轻型柴油发动机燃烧产生的，并在高温下被收集在紧接发动机之后的颗粒过滤器内部，这种材料对常规提取技术（例如索氏提取）具有特别的抵抗力，并且其提取行为与认证产品明显不同。参考资料（SRM 1650）。进行了析因实验设计，同时模拟了四个SFE实验因素对回收率的影响，即：超临界流体的温度和压力，添加到CO2中的有机改性剂的性质和百分比（氯仿，四氢呋喃， （二氯甲烷）作为达到所有研究目标污染物的最佳提取率的一种方法。建模结果表明，超临界流体压力必须保持在最高水平（30 MPa），温度必须保持相对较低（75°C）。在这些操作条件下，向CO2中添加15％的二氯甲烷不仅可以定量萃取轻质PAH及其硝化衍生物，而且还可以从加标的煤烟中定量萃取重链烷烃。但是，没有从耐火碳质固体表面定量提取重质芳香族化合物。因此，测试了原始的有机改性剂，包括吡啶，吡啶是最强的电子供体助溶剂（占二氧化碳的15％）。向吡啶中添加二乙胺可增强助溶剂的电子给体特性，甚至可提高最重PAH的提取率，从而可从柴油机颗粒物中定量提取所有PAH（超过79％），且具有检测限对于100 mg的加标物质，范围为0.5到7.8 ng。关于硝化的PAH，在吡啶中少量加入乙酸作为助溶剂可达到最佳效果，可实现合理的萃取收率（约60％），检出限为18至420 ng。

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