| 1. |
- Avagyan, Rozanna, 1988-
(författare)
-
From source to the environment : Strategies for identification and determination of hydroxylated polycyclic aromatic hydrocarbons in complex particulate matrices
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adverse health effects have been linked to exposure to particulate matter, and wood combustion is considered as an important source of harmful particulate matter in the urban air and environment. Hydroxylated polycyclic aromatic hydrocarbons are a group of compounds with toxic, endocrine disrupting and carcinogenic properties. Sources of hydroxylated polycyclic aromatic hydrocarbons are different incomplete combustion processes, such as coal and wood combustion. They can also be formed by microbiological and/or photochemical degradation of polycyclic aromatic hydrocarbons in the environment.This thesis describes analytical strategies and methods that have been developed and used for screening, tentative identification and determination of hydroxylated polycyclic aromatic hydrocarbons in wood combustion and urban air particles. Conventional targeted analytical methods have been developed for compounds with available reference standards, while suspect and non-target screening strategies have been used for the identification of suspects and unknown compounds lacking reference standards. Each step of the developed analytical methods is described and discussed: the choice of the analytical strategy, sampling of the matrices, extraction, clean-up, instrumental analysis, data processing and validation of the methods.The influence of wood type (birch, spruce, pine and aspen) and burning conditions (nominal and high burn rate) on the hydroxylated polycyclic aromatic hydrocarbon emissions has been examined, showing that emissions from nominal burn rate combustion correspond on average to 14 % of the emissions from high burn rate combustion. It has been shown that spruce and pine have the highest emissions for nominal burn rate and high burn rate combustion, respectively.The composition of wood combustion particles has been examined and 32 suspect hydroxylated polycyclic aromatic hydrocarbons have been tentatively identified together with 20 other oxygen-containing small molecular weight compounds. Furthermore, the presence of hydroxylated polycyclic aromatic hydrocarbons in airborne particles from an urban background and a car tunnel has been investigated, and nine target and 11 suspect hydroxylated polycyclic aromatic hydrocarbons have been determined and tentatively identified, respectively.In summary, this thesis has shown that wood combustion is an important emission source of hydroxylated aromatic hydrocarbons and that the chemical composition of the emitted particles strongly depends on both burning conditions and wood type. Furthermore, the findings suggest that there might be other sources of these compounds in the urban environment than wood burning, such as the traffic. Thus, further investigations are required to fully understand the formation, sources and presence of hydroxylated polycyclic aromatic hydrocarbons in the atmosphere. The suitability of different analytical strategies and methods for identification and determination of hydroxylated polycyclic aromatic hydrocarbons is also discussed.
|
|
| 2. |
- Masala, Silvia, 1971-
(författare)
-
Determination of Polycyclic Aromatic Hydrocarbons in Various Environmental Matrices : Emphasis on extraction method development
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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.
|
|
| 3. |
- Sadiktsis, Ioannis, 1982-
(författare)
-
Traffic related air pollution with emphasis on particle associated polycyclic aromatic hydrocarbons : Tire wear and biodiesel exhaust emissions
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Particulate matter (PM) is regarded as one of the more important components of air pollution causing adverse health effects. A large group of compounds associated with PM are polycyclic aromatic compounds (PACs) which comprises polycyclic aromatic hydrocarbons (PAHs). Several PACs are known for their mutagenic and carcinogenic properties as well as have the ability to induce oxidative stress.With the growing importance of non-exhaust particles relative to vehicular tail-pipe emissions in urban air, it is necessary to investigate the possible contribution of PAHs from the different non-exhaust sources, as these inputs are far less characterized than tail-pipe emissions and their impact on human health is largely unknown.In this thesis automobile tires, an important non-exhaust traffic related source to particles, have been investigated for its content of highly carcinogenic dibenzopyrene isomers. In a separate study benzothiazoles, a class of compounds used as vulcanization accelerators in tire manufacture, were determined to evaluate their use as potential markers for tire wear particles in ambient air.Analysis of the tires showed a substantial variation in the PAH content between different makes of tires, likewise did the benzothiazoles content vary. By determining benzothiazole in air particles collected at a busy street in Stockholm the tire rubber contribution to airborne particles was estimated to 0.7 and 5.5 % for PM10 and all airborne particles, respectively. Together with the determined content of dibenzopyrenes and the relatively low mass contribution of tire wear to airborne particles in the urban air, estimated in this thesis as well as suggested by the literature, tire wear appears to be a minor traffic related contributor of these PAH compounds in the urban air. Nevertheless, tire wear may be an important source to 2-mercaptobenzothiazole in the urban air.Biodiesel, a biofuel produced from plant and animal fats, has been suggested as a suitable replacement for conventional petroleum based diesel fuels. While the majority of studies have focused on health outcomes from petroleum diesel exhaust exposure, human health effects related to biodiesel exhaust exposure is much less investigated.Biodiesel exhaust particles have been compared with conventional petroleum diesel by determining >40 PAHs in two separate studies on two different diesel engines, running on neat rapeseed methyl ester (RME), petroleum diesel and a fuel blend of 3:7 RME : petroleum diesel. One of the biodiesel studies also included determination of four oxygenated PAHs (Oxy-PAHs).The exhaust from biodiesel combustion differed from petroleum diesel combustion with regards to particle size, number of emitted particles, relative amount of volatile material adsorbed on the particles and emission of particle-associated PAHs and Oxy-PAHs. A portion of these volatile compounds originated from unburned or partially combusted biodiesel fuel, which interfered with the analysis. A sample cleanup method was therefore developed for determination of PAH in lipid rich matrices. Biodiesel combustion produced lower emission of PAHs and Oxy-PAH with the exception of a few PAHs with higher molecular weights. In comparison with petroleum diesel, the biodiesel particles had a higher relative composition of PAHs with more than four rings.
|
|
| 4. |
- Lim, Hwanmi, 1977-
(författare)
-
Automation, hyphenation and multidimensional chromatography for PAH analysis : Analytical techniques to simplify sample complexity
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One group of organic environmental pollutants which are potentially hazardous to human health is polycyclic aromatic hydrocarbons (PAHs). These compounds consist of two or more benzene rings in their structure among which benzo[a]pyrene (B[a]P) is classified as a human carcinogen. In order to generate accurate data for PAHs, reliable analytical methods are a prerequisite for PAH monitoring in the environment and cancer risk assessments. However, there are several analytical challenges in PAH analysis because they are a large number of compounds with different physical and chemical properties and occur at varying concentration levels, often in complex matrices. Thus, this thesis aimed at tackling these difficulties in PAH analysis using various analytical techniques such as automation, hyphenation and multidimensional chromatography, particularly to increase the detectability and separation efficiency of PAHs in complex matrices. Furthermore, analytical methods were also presented as a tool for toxicological studies.A fully automated two-dimensional (2D)-liquid chromatography (LC)/2D-gas chromatography system was developed to enable the online sample clean-up, separation and detection, initially with two flame ionization detectors (FIDs) (Paper I). The introduction of mass selective detectors (MSDs) instead of two FIDs further advanced the original 2D system, improving the detectability and selectivity in PAH analysis (Paper II). The PAH levels were determined in two standard reference materials (SRMs) from the National Institute of Standards and Technology (NIST), i.e. urban dust (SRM 1649a) and diesel particulate extract (SRM 1975). The measured PAH levels were in good agreement with those obtained from FID- and MSD-based systems and reported by NIST (Paper I and II). Additionally, the PAH determination was done in particulates from wood burning, which also showed comparable results between FID and MSD systems (Paper II). The FID-based system showed slightly better separation efficiency owing to the use of hydrogen as carrier gas instead of helium and similar detectability to that of MSD (Paper I). However, the MSD-based system was advantageous to detecting late-eluting PAHs and separating interfering peaks in complex matrices (Paper II).Paper III presented an online LC system for B[a]P-selective fractionation as a tool for studying biological interactions. Fractions could be obtained from Stockholm air particulate matter (PM) extract with or without B[a]P. The selective fractionation was achieved using serial LC columns of two pyrenyl phases, resulting in more than 90% of B[a]P in the B[a]P-containing fraction. An analytical method for identification and quantification of benz[j]aceanthrylene (B[j]A) in air PM was developed and described in paper IV. B[j]A is rarely measured due to its low abundance but is known to have high carcinogenic potential. The determination of B[j]A in air PM from Stockholm (Sweden) and Limeira (Brazil), was done together with a series of toxicological studies. The measurement and toxicological data showed an increased number of estimated cancer cases from air PM exposure when levels of B[j]A were taken into account.In conclusion, this thesis presents various analytical approaches to obtain more accurate PAH data as well as the possibilities of using them in toxicological research.
|
|
| 5. |
- Mohammad Ahmed, Trifa, 1968-
(författare)
-
Determination of OPAHs and PAHs in Particulate Matter from Ambient Air and Engine Emissions : Multidimensional Chromatography
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Particulate matter (PM) is an air pollutant that seriously impacts human health. Epidemiological studies have shown associations between human exposure to urban air PM and lung cancer, respiratory and cardiovascular diseases. Polycyclic aromatic hydrocarbons (PAHs) and oxygenated polycyclic aromatic hydrocarbons (OPAHs) are two groups of compounds associated with PM in ambient air. These compounds are generated from the incomplete combustion of organic material of both natural and anthropogenic origin. PAHs are thought to play an important role in the adverse health outcomes from exposure to PM in air. OPAHs contain one or more carbonyl groups and could be more toxic to humans compared to their corresponding parent PAH. Measurement of these compounds at trace levels in complex matrices requires analytical methods with high selectivity and precision and low quantification limits.This thesis describes the development and application of analytical methods for the determination of PAHs and OPAHs in ambient air and engine exhaust PM. Extraction was performed using pressurized liquid extraction, and two different setups for liquid chromatography–gas chromatography (LC-GC) were employed for automated sample clean-up, separation and detection. The developed methods were validated using standard reference materials issued by the National Institute of Standards and Technology. The first methodology developed used off-line solid-phase extraction and on-line LC-GC/mass spectrometry (LC-GC/MS). This method provided low limits of quantification and high selectivity and was successfully applied to the determination of OPAHs and PAHs in PM from the urban atmosphere of Sulaymaniyah city in the Kurdistan region of Iraq. The concentration of benzo[a]pyrene in Sulaymaniyah city was three times higher than the legislated EU target value (1 ng/m3). Furthermore the analytical method was applied on exhaust PM of vehicles fuelled with various gasoline/ethanol blends. The emissions factors for PAHs and OPAHs were highest when using70% ethanol/gasoline blends at -7 °C.The second method developed provided fully automated clean-up, separation and detection of PAHs in PM extracts using a multidimensional 2D-LC/2D-GC system. Polar, mono/di-aromatic and alkane compounds were successively removed by the two-dimensional LC part of the system. Heart-cutting segments from the first GC column (first dimension) to the second GC column (second dimension) increased the resolution of poorly separated or co-eluted PAHs. The results were in good agreement with the certified values from NIST (±25%).
|
|
