Determination of Selected Polycyclic Aromatic Compounds in Particulate Matter Samples with Low Mass Loading: An Approach to Test Method Accuracy

Abstract

A miniaturized analytical procedure to determine selected polycyclic aromatic compounds (PACs) in low mass loadings (<10 mg) of particulate matter (PM) is evaluated. The proposed method is based on a simple sonication/agitation method using small amounts of solvent for extraction. The use of a reduced sample size of particulate matter is often limiting for allowing the quantification of analytes. This also leads to the need for changing analytical procedures and evaluating its performance. The trueness and precision of the proposed method were tested using ambient air samples. Analytical results from the proposed method were compared with those of pressurized liquid and microwave extractions. Selected PACs (polycyclic aromatic hydrocarbons (PAHs) and nitro polycyclic aromatic hydrocarbons (NPAHs)) were determined by liquid chromatography with fluorescence detection (HPLC/FD). Taking results from pressurized liquid extractions as reference values, recovery rates of sonication/agitation method were over 80% for the most abundant PAHs. Recovery rates of selected NPAHs were lower. Enhanced rates were obtained when methanol was used as a modifier. Intermediate precision was estimated by data comparison from two mathematical approaches: normalized difference data and pooled relative deviations. Intermediate precision was in the range of 10-20%. The effectiveness of the proposed method was evaluated in PM aerosol samples collected with very low mass loadings (<0.2 mg) during characterization studies from turbofan engine exhausts.

Environmental analysis of polar and non-polar Polycyclic Aromatic Compounds in airborne particulate matter, settled dust and soot: Part I: Sampling and sample preparation

“…Even if the interesting possibilities offered by PLE, particularly in terms of automation, have 374 increased its use over Soxhlet and sonication in recent years, sonication remains one of the 375 most frequent extraction methods. With the "classical solvents" cited in Section 3.1, quantitative extractions of PACs from particulate matters are achieved in less than an hour, even sometimes in less than 20 minutes [32,101,[121][122][123]. According to several works, the extraction recoveries obtained with UAE are similar to those obtained with Soxhlet extraction, but in a far shorter time [32,107,124].…”

“…When keeping the same solvent (dichloromethane), PLE and UAE gave comparable extraction yields. Even if they were slightly favorable to PLE, the authors reported the differences between both extractions as insignificant [121]. These results are presented in Figure 2, where the grey bars represent the quantities of analytes extracted by PLE with dichloromethane, and the darkest bars represent the quantities of analytes extracted by UAE with dichloromethane (abbreviated "AG-D").…”

“…The results obtained proved to be very heterogeneous. Indeed, as shown in Figure 2, whereas MAE gave the highest extraction recoveries for pyrene and benzo[b]fluoranthene, it was totally ineffective for benzo[a]pyrene and 3-nitrofluoranthene [121]. Barrado et al reported higher extraction yields of PAHs in dichloromethane with the use of a microwave device than with ultrasound or Soxhlet extractors [127].…”

“…The developments of this technique are relatively recent, so that in the review of Walgraeve Recently, more and more groups studying polar and non-polar PACs in particulates have utilized MAE [37,45,59,121,127,129]. Similarly to PFE, this technique enables the heating of an organic solvent above its boiling point to enhance the extraction, thanks to specially adapted vessels placed in a microwave oven.…”