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Class separation of lipids and polycyclic aromatic hydrocarbons in normal phase high performance liquid chromatography - A prospect for analysis of aromatics in edible vegetable oils and biodiesel exhaust particulates
Stockholm University, Faculty of Science, Department of Analytical Chemistry.
Stockholm University, Faculty of Science, Department of Analytical Chemistry.ORCID iD: 0000-0002-1598-7093
Stockholm University, Faculty of Science, Department of Analytical Chemistry.
Stockholm University, Faculty of Science, Department of Analytical Chemistry.
2014 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1360, 39-46 p.Article in journal (Refereed) Published
Abstract [en]

The retention characteristics of the major lipid components in biodiesels and edible oils as well as representative polycyclic aromatic compounds (PAHs) have been investigated on five different normal phase HPLC stationary phases, in order to optimize class separation for an automatized online HPLC cleanup of PAHs prior GC-MS analysis. By stepwise comparison of different hexane/MTBE compositions as mobile phases on cyano-, phenyl-, pentabromobenzyl-, nitrophenyl- and amino- modified silica columns, the capacity and selectivity factors for each analyte and column could be calculated. It was concluded that the most suitable column for backflush isolation of PAHs in biodiesel and edible oil matrices was the pentabromobenzyl-modified silica (PBB). A previously described online HPLC-GC-MS system using the PBB column was then evaluated by qualitative and quantitative analysis of a biodiesel exhaust particulate extract and a vegetable oil reference material. The GC-MS full scan analysis of the biodiesel particulate extract showed that the lipids had been removed from the sample and a fraction containing PAHs and oxygenated derivatives thereof had been isolated. Quantified mass fractions of PAHs of the reference material BCR-458 agreed well for most of the certified PAH mass fractions in the spiked coconut oil reference material.

Place, publisher, year, edition, pages
2014. Vol. 1360, 39-46 p.
Keyword [en]
Biodiesel particulates, Edible oils, Fatty acid methyl esters, Sample cleanup, High performance liquid chromatography
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
URN: urn:nbn:se:su:diva-106272DOI: 10.1016/j.chroma.2014.07.064ISI: 000341469400005OAI: oai:DiVA.org:su-106272DiVA: diva2:735582
Available from: 2014-07-29 Created: 2014-07-29 Last updated: 2017-12-05Bibliographically approved
In thesis
1. Essentially Lipids: Analytical methods for the characterization of lipid materials
Open this publication in new window or tab >>Essentially Lipids: Analytical methods for the characterization of lipid materials
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes analytical methods for chromatographic characterizations of lipids in biological and technical systems.

Lipids are a group of compounds with a central role in all known forms of life. In addition to the biological roles, lipids are also components in many products of our daily usage. The application areas include food, pharma, cosmetics, biofuels, etc.

Analytical characterization of lipids is challenging since a typical lipid extract often contains several hundred unique compounds which also could vary significantly in chemical properties. Separation is in many cases crucial for identification and quantification of individual lipids and here high performance liquid chromatography (HPLC) is regarded as the technique of first choice today.

In the present work, methodologies for both normal phase (NP) and reversed phase (RP) HPLC are presented. The focus has been to develop methods that are fast, have low analytical complexity and are compatible with several detection systems. Cyanopropyl coated silica was evaluated as stationary phase for NP-HPLC with the aim to separate all the lipid classes in common lipid extracts. The analytes were eluted with a binary mobile phase system based on hexane, toluene and methanol which yielded in a total runtime of 30 minutes. In a subsequent study, additional stationary phases for NP-HPLC were evaluated for online sample cleanup of polycyclic aromatic hydrocarbons (PAHs) in lipid matrixes. In the demonstrated methodology for RP-HPLC, a binary system consisting of methanol/water was utilized with phenylpropyl coated silica to elute all tested lipid classes in 30 minutes.

The methodologies were compatible with various detection techniques including evaporative light scattering detection (ELSD), charged aerosol detection (CAD) as well as electrospray mass spectrometry (ESI-MS) and were applied to characterize lipid materials of both biological and technical nature. 

Place, publisher, year, edition, pages
Stockholm: Department of Environmental Science and Analytical Chemistry, Stockholm Univeristy, 2015. 49 p.
Keyword
Lipids, Chromatography, HPLC, Charged Aerosol Detection, Evaporative light scattering detection, mass spectrometry
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:su:diva-113052 (URN)978-91-7649-077-8 (ISBN)
Public defence
2015-02-27, Magnélisalen, Kemiska Övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (Swedish)
Opponent
Supervisors
Available from: 2015-02-05 Created: 2015-01-22 Last updated: 2015-01-28Bibliographically approved
2. Traffic related air pollution with emphasis on particle associated polycyclic aromatic hydrocarbons: Tire wear and biodiesel exhaust emissions
Open this publication in new window or tab >>Traffic related air pollution with emphasis on particle associated polycyclic aromatic hydrocarbons: Tire wear and biodiesel exhaust emissions
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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. 

Place, publisher, year, edition, pages
Stockholm: Department of Environmental Science and Analytical Chemistry, Stockholm University, 2016
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:su:diva-128859 (URN)978-91-7649-374-8 (ISBN)
Public defence
2016-05-25, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.

Available from: 2016-05-02 Created: 2016-04-06 Last updated: 2017-02-24Bibliographically approved

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