Laboratoire d'Analyse des Systèmes organiques Complexes, IRCOF et IFRMP, Université de Rouen, 55 rue Saint Germain, 27000 Evreux, France.
Talanta. 2010 Jun 30;82(1):227-36. doi: 10.1016/j.talanta.2010.04.027. Epub 2010 Apr 22.
Several methods of extraction were optimized to extract polycyclic aromatic hydrocarbons (PAHs), their nitrated derivatives and heavy n-alkanes from a highly adsorptive particulate matter resulting from the combustion of diesel fuel in a diesel engine. This particular carbonaceous particulate matter, collected at high temperatures in cordierite diesel particulate filters (DPF), which are optimized for removing diesel particles from diesel engine exhaust emissions, appeared extremely refractory to extractions using the classical extracting conditions for these pollutants. In particular, the method of accelerated solvent extraction (ASE) is described in detail here. Optimization was performed through experimental design to understand the impact of each factor studied and the factors' possible interactions on the recovery yields. The conventional extraction technique, i.e., Soxhlet extraction, was also carried out, but the lack of quantitative extractions led us to use a more effective approach: hot Soxhlet. It appeared that the extraction of the heaviest PAHs and nitroPAHs by either the optimized ASE or hot Soxhlet processes was far from complete. To enhance recovery yields, we tested original solvent mixtures of aromatic and heteroaromatic solvents. Thereafter, these two extraction techniques were compared to microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE). In every case, the only solvent mixture that permitted quantitative extraction of the heaviest PAHs from the diesel soot was composed of pyridine and diethylamine, which has a strong electron-donor character. Conversely, the extraction of the nitrated PAHs was significantly improved by the use of an electron-acceptor solvent or by introducing a small amount of acetic acid into the pyridine. It was demonstrated that, for many desirable features, no single extraction technique stound out as the best: ASE, MAE or SFE could all challenge hot Soxhlet for favourable extractions. Consequently, the four optimized extraction techniques were performed to extract the naturally polluted diesel soot collected inside the DPF. Comparisons with the NIST standard reference material SRM 1650b showed that the soot collected from the DPF contained 50% fewer n-alkanes, and also markedly lower levels of PAHs (44 less concentrated) than SRM 1650b, and that the ratio of nitroPAHs to PAHs was increased. These results were attributed to the high temperatures reached inside the particulate filter during sampling runs and to the contribution of the catalytic DPF to aromatic and aliphatic hydrocarbons abatement.
几种提取方法被优化，以从柴油机燃烧产生的高度吸附的颗粒物中提取多环芳烃（PAHs）、其硝化衍生物和重正构烷烃。这种特殊的含碳颗粒物，在堇青石柴油颗粒过滤器（DPF）中以高温收集，DPF 经过优化，可从柴油机废气排放中去除柴油机颗粒，在使用这些污染物的经典提取条件进行提取时，表现出极高的抗提取性。特别是，本文详细描述了加速溶剂萃取（ASE）方法。通过实验设计进行了优化，以了解每个研究因素的影响以及因素之间的可能相互作用对回收产率的影响。还进行了传统的萃取技术，即索氏萃取，但由于定量萃取的缺乏，我们使用了更有效的方法：热索氏萃取。结果表明，通过优化的 ASE 或热索氏萃取过程提取最重的 PAHs 和硝基 PAHs 远未完全。为了提高回收产率，我们测试了芳烃和杂芳烃溶剂的原始溶剂混合物。此后，将这两种提取技术与微波辅助提取（MAE）和超临界流体萃取（SFE）进行了比较。在每种情况下，唯一能够从柴油烟尘中定量提取最重 PAHs 的溶剂混合物由吡啶和二乙胺组成，它们具有很强的供电子特性。相反，通过使用电子受体溶剂或在吡啶中引入少量乙酸，显著改善了硝基 PAHs 的提取。结果表明，对于许多理想的特性，没有一种单一的提取技术脱颖而出：ASE、MAE 或 SFE 都可以挑战热索氏萃取以获得有利的提取效果。因此，对四种优化的提取技术进行了提取，以提取在 DPF 内部收集的天然污染的柴油烟尘。与 NIST 标准参考物质 SRM 1650b 的比较表明，从 DPF 收集的烟尘中 n-烷烃含量减少了 50%，并且与 SRM 1650b 相比，PAHs 的含量也明显降低（浓度降低了 44%），并且硝基 PAHs 与 PAHs 的比例增加。这些结果归因于采样过程中在颗粒过滤器内部达到的高温以及催化 DPF 对芳烃和脂肪烃减排的贡献。
