Evaluation of the efficiency of extraction of PAHs from diesel particulate matter with pressurized solvents

Abstract

Pressurized Fluid Extraction (PFE) was evaluated for the extraction of polycyclic aromatic hydrocarbons (PAHs) and nitro-derivatives from diesel particulate matter. Extraction conditions were set up by performing several tests in which temperature, solvent strength, pressure, and static time were gradually increased. The results obtained on a laboratory test material made of a "lean" (low content of soluble fraction) Diesel particulate matter indicate that very severe conditions were needed in order to obtain better recoveries of the higher molecular weight molecules. Moreover, extraction efficiency seems to be influenced by the amount of soluble matter in the particulate, so that a "lean" particulate appears more difficult to extract. Recoveries of the deuterated standards of certain PAHs (i.e. indeno[1,2,3- cd]pyrene) were incomplete even with the toughest conditions tested. Experiments carried out on a certified material (SRM 1650 from NIST) also indicate that PFE can perform a better extraction of some of the PAHs than the method used for certification, but still incomplete. Comparison of results obtained on the SRM with different extraction techniques suggests that the composition of the extract varies considerably with the extraction technique and conditions. It is relevant to notice that recent Diesel engines produce leaner particulate: for future materials more drastic extraction conditions will be required.

High-Precision GC-MS Analysis of Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) and Isomer Ratios from Biomass Burning Emissions

“…An alternative extraction technique involving supercritical fluid extraction (SFE) requires longer extraction time and also suffers from the incomplete recovery of PAHs in environmental samples due to analyte-matrix interactions [21]. In contrast, the microwave-assisted solvent extraction (MASE) and the accelerated solvent extraction (ASE) approach are beneficial in terms of lower consumption of solvent and perform extraction in shorter time [12,15,[22][23][24]. However, the MASE technique requires centrifugation and filtration; thus, amounting to the loss of analyte.…”

Analytical Methods for Determination of Polycyclic Aromatic Hydrocarbons (PAHs) — A Historical Perspective on the 16 U.S. EPA Priority Pollutant PAHs

“…In Because of these reported higher extraction recoveries for higher molecular mass PAHs using PLE for SRM 1649a, SRM 1650b, and SRM 2975 (76,78,77), Schantz et al (79) performed a comprehensive investigation of the different PLE parameters (solvent, number of static cycles and static times, pressure, and temperature) for the extraction of PAHs and nitrated-PAHs from two urban particulate matter SRMs (SRM 1648a and SRM 1649b) and from two diesel particulate matter SRMs (SRM 1650b and SRM 2975). The results showed that temperature was the most significant parameter for PLE of the air particulate SRMs and that for the majority of PAHs greater recoveries (generally about 10% higher) could be obtained at temperatures of 150 • C and 200 • C (the maximum temperature of current commercial PLE instrumentation).…”

Analytical Methodologies for the Control of Particle-Phase Polycyclic Aromatic Compounds from Diesel Engine Exhaust

“…Indeed, in this case, the sorption is dominated by strong surface adsorption while a high amount of SOF attenuates PAHs adsorption, blocking the energetic sites, and thus a simple phase partitioning dominates [103]. Consequently, the presence on the particles of relevant amounts of SOF helps the solvent extraction process; however, it is now relevant to notice that recent diesel engines that are equipped with oxidation catalysts and particulate filters produce leaner particulates, and as it previously mentioned, more drastic extraction conditions are required [61]. Therefore, in the future, it will be important to pay more attention on the optimisation of the extraction step to obtain quantitative results, especially for the highest weight and more toxic PAHs and nitro-PAHs.…”

“…Elevated temperatures (150-200°C) permit to disrupt the strong solute-matrix interactions, and a high pressure (100-150 bars) forces the extraction solvent into the matrix pores. Less than 20 mL of solvent can be used to extract PAHs and nitro-PAHs from diesel PM; extractions with toluene [61], methylene chloride [16] or less conventional solvents based on pyridine [60] were performed. Extraction apparatus (a) Microwave-Assisted Extraction: MAE extraction vessels are placed on a turntable inside an oven and are subjected to microwave irradiations generated by a magnetron.…”