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- Masala, Silvia, 1971-
(author)
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Determination of Polycyclic Aromatic Hydrocarbons in Various Environmental Matrices : Emphasis on extraction method development
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Very recently, air pollution was declared the world’s single largest environmental health risk by the World Health Organization. The goal of this thesis is to contribute to a better assessment of air pollution through the development of novel and exhaustive extraction methods for the analysis of polycyclic aromatic hydrocarbons (PAHs), which are mutagenic and carcinogenic air pollutants.The methods were developed and validated for the extraction of PAHs in both the semi-volatile fraction and particulate matter with application to samples derived from major sources of PAHs (diesel exhaust, coal fly ash and wood smoke samples). Pressurized liquid extraction was used because it allows a high sample throughput with reduced solvent requirements and analysis time compared to other traditionally used techniques, such as Soxhlet extraction.The results presented herein show that the extraction conditions used when analyzing PAHs need to be evaluated to avoid underestimating their concentrations. This is especially true for the human carcinogen benzo[a]pyrene, which is often used as an indicator in the cancer risk assessments of PAHs, and the dibenzopyrene isomers due to their potentially high carcinogenicities.
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| 3. |
- Titaley, Ivan A., et al.
(author)
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Extensive chemical and bioassay analysis of polycyclic aromatic compounds in a creosote-contaminated superfund soil following steam enhanced extraction
- 2022
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In: Environmental Pollution. - : Springer. - 0269-7491 .- 1873-6424. ; 312
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Journal article (peer-reviewed)abstract
- Polycyclic aromatic compounds (PACs) are organic compounds commonly found in contaminated soil. Previous studies have shown the removal of polycyclic aromatic hydrocarbons (PAHs) in creosote-contaminated soils during steam enhanced extraction (SEE). However, less is known about the removal of alkyl-PAHs and heterocyclic compounds, such as azaarenes, and oxygen- and sulfur-heterocyclic PACs (OPACs and PASHs, respectively). Further, the impact of SEE on the freely dissolved concentration of PACs in soil as well as the soil bioactivity pre- and post-SEE have yet to be addressed. To fulfil these research gaps, chemical and bioanalytical analysis of a creosote-contaminated soil, collected from a U.S. Superfund site, pre- and post-SEE were performed. The decrease of 64 PACs (5-100%) and increase in the concentrations of nine oxygenated-PAHs (OPAHs) (150%) during SEE, some of which are known to be toxic and can potentially contaminate ground water, were observed. The freely dissolved concentrations of PACs in soil were assed using polyoxymethylene (POM) strips and the concentrations of 66 PACs decreased post-SEE (1-100%). Three in vitro reporter gene bioassays (DR-CALUX®, ERα-CALUX® and anti-AR CALUX®) were used to measure soil bioactivities pre- and post-SEE and all reporter gene bioassays measured soil bioactivity decreases post-SEE. Mass defect suspect screening tentatively identified 27 unique isomers of azaarenes and OPAC in the soil. As a remediation technique, SEE was found to remove alkyl-PAHs and heterocyclic PACs, reduce the concentrations of freely dissolved PACs, and decrease soil bioactivities.
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- Titaley, Ivan, 1990-, et al.
(author)
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Automating data analysis for two-dimensional gas chromatography/time-of-flight mass spectrometry non-targeted analysis of comparative samples
- 2018
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In: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1541, s. 57-62
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Journal article (peer-reviewed)abstract
- Non-targeted analysis of environmental samples, using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC x GC/ToF-MS), poses significant data analysis challenges due to the large number of possible analytes. Non-targeted data analysis of complex mixtures is prone to human bias and is laborious, particularly for comparative environmental samples such as contaminated soil pre- and post-bioremediation. To address this research bottleneck, we developed OCTpy, a Python (TM) script that acts as a data reduction filter to automate GC x GC/ToF-MS data analysis from LECO (R) ChromaTOF (R) software and facilitates selection of analytes of interest based on peak area comparison between comparative samples. We used data from polycyclic aromatic hydrocarbon (PAH) contaminated soil, pre- and post-bioremediation, to assess the effectiveness of OCTpy in facilitating the selection of analytes that have formed or degraded following treatment. Using datasets from the soil extracts pre- and post-bioremediation, OCTpy selected, on average, 18% of the initial suggested analytes generated by the LECO (R) ChromaTOF (R) software Statistical Compare feature. Based on this list, 63-100% of the candidate analytes identified by a highly trained individual were also selected by OCTpy. This process was accomplished in several minutes per sample, whereas manual data analysis took several hours per sample. OCTpy automates the analysis of complex mixtures of comparative samples, reduces the potential for human error during heavy data handling and decreases data analysis time by at least tenfold. (C) 2018 Elsevier B.V. All rights reserved.
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| 5. |
- Titaley, Ivan, 1990-, et al.
(author)
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Evaluating Computational and Structural Approaches to Predict Transformation Products of Polycyclic Aromatic Hydrocarbons
- 2019
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:3, s. 1595-1607
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Journal article (peer-reviewed)abstract
- Polycyclic aromatic hydrocarbons (PAHs) undergo transformation reactions with atmospheric photochemical oxidants, such as hydroxyl radicals (OH center dot), nitrogen oxides (NOx), and ozone (O-3). The most common PAH-transformation products (PAH-TPs) are nitrated, oxygenated, and hydroxylated PAHs (NPAHs, OPAHs, and OHPAHs, respectively), some of which are known to pose potential human health concerns. We sampled four theoretical approaches for predicting the location of reactive sites on PAHs (i.e., the carbon where atmospheric oxidants attack), and hence the chemoselectivity of the PAHs. All computed results are based on density functional theory (B3LYP/6-31G(d) optimized structures and energies). The four approaches are (1) Clar's prediction of aromatic resonance structures, (2) thermodynamic stability of all OHPAH adduct intermediates, (3) computed atomic charges (Natural Bond order, ChelpG, and Mulliken) at each carbon on the PAH, and (4) average local ionization energy (ALIE) at atom or bond sites. To evaluate the accuracy of these approaches, the predicted PAH-TPs were compared to published laboratory observations of major NPAH, OPAH, and OHPAH products in both gas and particle phases. We found that the Clar's resonance structures were able to predict the least stable rings on the PAHs but did not offer insights in terms of which individual carbon is most reactive. The OHPAH adduct thermodynamics and the ALIE approaches were the most accurate when compared to laboratory data, showing great potential for predicting the formation of previously unstudied PAH-TPs that are likely to form in the atmosphere.
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