Portet-Koltalo F, Oukebdane K, Dionnet F, Desbène P L
Laboratoire d'Analyse des Systèmes Organiques Complexes, IRCOF et IFRMP, Université de Rouen, 55 rue Saint Germain, 27000 Evreux, France.
Anal Chim Acta. 2009 Sep 28;651(1):48-56. doi: 10.1016/j.aca.2009.07.038. Epub 2009 Jul 22.
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 CO(2) (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 degrees C). Under these operating conditions, adding 15% of methylene chloride to the CO(2) permitted quantitative extraction of not only light PAHs and their nitrated derivatives, but also heavy n-alkanes from the spiked soots. However, heavy polyaromatics 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 CO(2)), 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.
采用超临界流体萃取（SFE）法从柴油不完全燃烧产生的加标烟尘颗粒中提取多环芳烃（PAHs）、硝化衍生物（硝基PAHs）和重质正构烷烃的复杂混合物。这种污染物质是由轻型柴油发动机燃烧产生的，并在发动机后的颗粒过滤器内高温收集，它对传统萃取技术（如索氏萃取）具有特别强的抗性，其萃取行为与标准参考物质（SRM 1650）明显不同。进行了析因实验设计，同时模拟四个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），以此达到所有研究目标污染物的最佳萃取产率。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℃）。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PAHs及其硝化衍生物，还可以从加标烟尘中定量萃取重质正构烷烃。然而，重质多环芳烃不能从难熔碳质固体表面定量萃取。因此，对原始有机改性剂进行了测试，包括吡啶，作为强电子供体共溶剂（15%加入CO₂），它最为成功。向吡啶中添加二乙胺，增强了共溶剂的电子供体特性，甚至提高了最重PAHs的萃取产率，从而从柴油颗粒物中定量萃取了所有PAHs（超过79%），100 mg加标物质的检测限为0.5至7.8 ng。对于硝基PAHs，向吡啶中少量添加乙酸作为共溶剂，效果最佳，萃取产率适中（约60%），检测限为18至420 ng。
