Biocatalytic methods of synthesis are becoming increasingly important in industry. Using enzymes as catalysts allows highly selective reactions to be performed under milder physical conditions and in a more environmentally benign fashion than most corresponding chemical catalysts. Enzymes have in general evolved to perform one type of reaction on a limited set of molecules, and hence there is often a need to alter the specificity of an enzyme to suit a desired process. Understanding the details of enzymatic catalysis at a quantum mechanical level enables the intelligent redesign of these macromolecules. For this purpose, density functional theory (DFT) has been shown to epitomise a suitable balance of accuracy and computational cost. Thus, this thesis describes the quantum chemical rationalisation of the reaction mechanism and sources of selectivity of the bacterial alcohol dehydrogenase TbSADH – an enzyme highly suited to modification for industrial processes. ADHs catalyse reversibly the interconversion of alcohols and ketones or aldehydes. Herein, the general ADH reaction mechanism was shown to be viable for this enzyme. In addition, the experimental enantiopreference of the enzyme was reproduced, and thus the reversal of selectivity seen with the slight increase in substrate size was captured. The main determinant of selectivity was found to be a fine balance of repulsive steric interactions and attractive dispersion effects between the substrate and the hydrophobic binding pockets. The ability of the modelling methodology to capture effects such as these represents further evidence of its usefulness as a complement to experimental work in designing the biocatalysts of the future. The development of protocols to allow quantum mechanical investigation of the production of large and industrially interesting axially chiral alcohols is also presented. The work described has showed that quantum chemical models of many hundreds of atoms are now within our grasp, and although they were unable to correctly describe the selectivity for the large 4-(bromomethylene)cyclohexan-1-one in TbSADH, the protocols devised can be very useful for future investigations of enzymatic catalysis.

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Due to the high temperatures during a fire event, a large variety of compounds are formed or released from burning materials, all of which have a varying degree of environmental effects. In an incidental fire there are several variables that are important for which and how much combustion products that are formed, including the burning material, ventilation (presence of air), and temperature. The aim of this project is to evaluate if there is a difference between formed fire residues in gas and soot using four different fire extinguishing techniques. A non-target approach is used with gas chromatography connected with ultrahigh-resolution mass spectrometry. Unlike target analysis, non-target analysis enables identification of not only known chemicals, but also previously unknown chemicals. However, one of the major challenges in non-target analysis is how to handle the large amount of data generated in order to identify important markers for the current research question. Mass defect filtering is used to interpret the complex mass spectral data. Plotting the mass defect against the measured m/z allows you to visualize a high number of mass spectral peaks, linking homologues and congeners. The plot is based on a specific mass scale and can be used to find m/z that belong to compounds of a specific compound group. Statistical methods such as Principle Component Analysis (PCA) are also useful as it extracts and displays systematic variation in a data set, which can be used to find interesting variables. Mass defect filtering proved to be useful for the detection of a number of different compound groups: Alkylated hydrocarbons, halogenated compounds and PAHs. There were several differences in the composition of the gas versus soot. Gas had little variation between the samples whereas soot varied more depending on firefighting method used. Despite the fact that the chemical composition of gas and soot does differ between the four firefighting techniques, the variations in wind conditions made it hard to draw any conclusions regarding how the different firefighting techniques affect the compound formation and to what extent.

Per- and polyfluoroalkyl substances (PFASs) have been used broadly in industries, firefighting foams, surfactant materials and consumer products. These compounds are very resistant to degradation in the environment and high exposure to these compounds may cause health issues such as cancer and immunosuppression. Many of the consumer products will end up as waste and later end up in landfills where the leachate will be contaminated by these compounds. The leachate can be dispersed to the surrounding environment, and it is therefore necessary to investigate and reduce the concentrations of PFAS in the landfill leachates. This study examined eight composite samples from eight different sample sites; the samples was originally from eight samples per sample site at a hazardous waste management facility collected at different time points, where 23 PFASs and extractable organic fluorine (EOF) were analysed. The concentrations of the total target PFASs ranged from 676-11 800 ng/L and the dominating compounds were short-chain perfluoroalkyl sulfonic acids (PFSAs), where perfluorobutane sulfonic acid (PFBS) had the highest concentration in most samples. These results were compared with another on-going study that analysed the same sample sites with grab samples collected at different time points. The comparison was made on the average of three grab samples from each sample site and it showed that the results from the grab samples and composite samples were similar in terms of number of detected compounds but not exact in concentrations. Depending on the objective of the monitoring, it is possible to use composite samples to save money and time. The study also showed that 80% of the EOF in all samples, except one, were unidentified which implies that the water samples might consist of high amounts of PFASs not in the target list, or other fluorinated compounds with similar properties to PFAS, which needs to be investigated, monitored and might be reduced in the environment.

The exposome is a complex study that includes both endogenous and exogenous markers related to different diseases as part of the research. Connecting both endogenous and exogenous markers can help explain many associations between environmental chemicals and metabolic profiles, which can be stressors for causing different diseases. This study investigates the impact of per- and polyfluorinated alkyl substances (PFAS) exposure during pregnancy on lipid profiles and measures the concentrations in blood and also in infants cord blood at birth. In addition, we are interested in lipids and bile acids (BA) levels in blood and if these three groups of analytes of interest are associated with each other. The infant blood-based samples come from a Chinese cohort and the maternal samples are from a Finnish cohort. The samples were extracted for PFAS and BA and for lipid analysis. Statistical analysis was performed for both cohorts. The main interest was to investigate the interactions between the identified compounds. The results also include concentrations to show the variety of values measured.  Type 2 diabetes (T2D) and non-alcoholic fatty-liver disease (NAFLD) are usually not acquired early in life. Our results show a strong positive correlation between PFASs and triglycerides (TGs), as well as strong correlation between PFASs and conjugated primary and secondary BA particularly in cord blood samples, which can indicate higher risk of developing T2D or NAFLD. In maternal samples, the interactions between PFASs, BAs and lipids were much lower and showed less significant correlation. This indicates that the impact of PFAS exposure is much stronger during fetal development than in adult life.

Type one diabetes (T1D) and islet autoimmunity (IA) in people with a genetically susceptibility for the diseases can be triggered by environmental factors. It is earlier showed that the diet can be one of the environmental factors as it has been indicated that a cereal rich diet can increase the risk of developing IA. In this study, we investigated blood plasma samples from a study done by L. Hakolas on children that have genetic risk of developing T1D and IA, with a focus on dietary contaminants originating from cereals. Mycotoxins often found on cereals could be one of the environmental factors triggering the development of the diseases. To see if this could be the case a method based on a liquid chromatography coupled with a quadrupole-time of flight (LC-QTOF) was developed for the analysis of mycotoxins and glyphosate; MS/MS mode was used after that to confirm the identity of the compounds. For sample preparation, protein precipitation of the plasma samples was applied. The method was optimized by analyzing 5 mycotoxin standards and a list of suspected compounds that could be found in the screening to make sure the method could separate all the compounds. Test plasma samples was also analyzed to determine the optimal plasma volume (100 mL) for extraction and injection volume (15mL). For the data preprocessing, MZmine software was used and could tentatively identify some of the mycotoxins based on accurate mass acquisition. After comparing the signal against the background noise, Ergotaminine, FB1, Gly and HT-2 and NIV were identified. As quality control three replicates of a pooled sample were analysed, using both positive and negative ionization modes. From the pooled sample mean, standard deviation (STD) and relative standard deviation (RSD) were calculated showing some variation among the plasma sample for some mycotoxins e.g., Gly. The results presented in this report show that some mycotoxins do occur in the blood plasma and that the amounts of the mycotoxins varied. However, how these mycotoxins can affect the progress of T1D and IA is still unknown and requires further studies.

Monitoring methods for environmental pollutants are mostly performed with targeted analysis which relies on predetermined compounds. This can cause an underestimation of possible toxicants as it might not detect undiscovered compounds such as breakdown products of other chemicals. Non-target analysis (NTA) has gained more attraction due to increasing instrumental sensitivity and technological advancements. It attempts to analyze the whole matrix without a prior selection of specific compounds. The aim of this project was to develop a sample preparation method that allows for biomonitoring of organic pollutants in fish using NTA. The method included a broad range of compounds that are suitable for gas chromatography-mass spectrometry (GC-MS) analysis. Five extraction techniques and three clean-up methods were compared using wet weight fish samples and spiked blank samples. The effectiveness of these methods was evaluated based on a selection of 60 compounds that cover the log Kow range of 0.8 to 8.3. The method best equipped for NTA after evaluating recovery and matrix effects was sonication extraction (extracted with a mixture of n-hexane/dichloromethane (DCM)) combined with a deactivated silica clean-up (eluted with n-hexane and DCM). The average recoveries for wet weight fish samples were 99 % for log Kow <5, 65% for log Kow 5-7, and 54% for log Kow ≥7. Semi quantification of nine compounds detected in the non-spiked fish was carried out. The sonication extraction result was statistically similar to the open column extraction but used less solvent than the other sample preparation procedures and was less time consuming. Deactivated silica clean-up is more comprehensive than the commonly used multi-layered silica clean-up and therefore more likely not to discriminate unknown compounds. Further non-target studies using the proposed method is required to evaluate its effectiveness.

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No description available.