Microwave-enhanced extraction is gaining in popularity because it allows for faster extraction, reduced solvent use, and high recovery efficiency compared to traditional methods such as Soxhlet extractions. The elevated temperatures and pressures applied to samples during microwave-enhanced extraction have the potential to accelerate abiotic degradative reactions producing artifactual apparent breakdown products absent from the original samples. In addition, humic substances have been shown to shuttle electrons between donors and acceptors. Because chlorinated organic compounds have proven to be good electron acceptors and because ferrous iron is often present in anoxic soils, the possibility appeared to exist that reductive dechlorination of chloroorganic compounds in samples of anaerobic soils and that this degradative reaction could be accelerated by the conditions applied during microwave-enhanced extraction. Aqueous solutions of between 10 and 40 μg of PCP per ml were subjected to wide ranges of temperatures and pressures in the presence of 0.4 mg/ml of humic acid extracted from a commercial peat, in the presence of 400 μg/ml of FeSO4·7H2O, in the presence of both humic acid and ferrous iron, and in the presence of neither. These four treatments were tested for four days at room temperature. These treatments were also microwaved for 30 min. at 121, 145, and 170°C, for four hours at 160, and 170°C, and for one hour at 190°C, which was the operational upper limit of the microwave-extraction, pressure vessels. In none of the four treatments, following none of the time and temperature programs, were any additional apparent dechlorination products detected. Changing the solvent from water to ethyl acetate before microwaving 40 μg/ml PCP for 30 min. also failed to promote dechlorination. Microwaving a 20-μg/ml, aqueous solution of 2,3,4-trichlorophenol with the same combinations of humic acid and ferrous iron also failed to produce any evidence of reductive dechlorination. Four hours of microwaving at 160°C also failed to effect dechlorination of either 20 μg/g of PCP in any of four different soils or of 20 μg/ml of PCP in the usual four treatments in which the peat humic acid was replaced by Aldrich humic acid.

Ab initio calculations were utilized to demonstrate the theory behind molecular properties and were correlated to actual spectroscopic results in the infrared and Raman. Symmetrical aspects of small flexible molecules were examined to determine how symmetry coordinates mix in the potential energy distribution and whether these are infrared and Raman active. The difficulty is the spectroscopic landscape of the spectrum gets extremely complicated even in very small carbon chain dihalides. The example of 1,4-dichlorobutane is provided. The work here will provide a solid reference for future research as we have found in previous work that 1,2-dibromopropane, a sensitive compound, has in previous publications shown what looks to be degradation. Three other publications are in preparation allyldichlorosilane, n-butylgermane and n-butylsilane of which the two finial compounds have conformers with the same symmetry. Instrumentation has been updated to be continually maintained and upgraded to be viable and competitive. Times for crystallizations of spectroscopic compounds for the IR and Raman cold cells can exceed 50-60 hours of continuous annealing. Modification and development of equipment allowed a level of automation and a much more precise temperature control at lower temperatures that would not have been possible before.

Studies of the properties of metal cyclopentadienyl compounds were made by infra-red spectroelectrochemistry, electrochemistry, synthesis and $\sp{103}$Rh nuclear magnetic resonance spectrometry. A cell capable of simultaneously recording IR spectra of the region near the electrode surface during electrochemical experiments was developed, and characterized using ferricyanide. The absorbance-time response to potential step and potential sweep experiments was investigated and the experimentally determined response compared to a digital simulation of the response at different distances from the electrode surface. This allowed the distance from the electrode surface to the point of observation to be estimated. The capabilities of the cell were applied to the elucidation of the electrochemical behavior of titanocene dichloride and iron pentacarbonyl. Titanocene dichloride was reduced under an atmosphere of carbon monoxide to titanocene dicarbonyl and ultimately to the anion (CpTi(CO)$\sb4$) $\sp{-}$. No evidence for the formation of a titanium(III) carbonyl species was found. In contrast, reduction of titanocene dichloride in the presence of 2,6-dimethylphenylisocyanide led to the formation of titanium(III) and titanium(II) products, in which one and both of the chloride ligands had been replaced by the isocyanide, respectively. Electrochemical and chemical reduction of fulvalene-dititanium cyclopentadienyl compounds led to the breakage of the carbon-carbon bond linking the two five-membered rings of the fulvalene ligand. The electrochemical properties of a series of ferrocene-containing polyesters in solution was investigated using various stationary and rotating solid electrode techniques. The oxidised form of the polyesters coated the electrode surface in an uneven fashion allowing solution and surface processes to occur simultaneously. Evidence for the nature of this coating was gathered using X-ray photoelectron spectroscopy. The effect of substituents on a series of ring-substituted (h$\sp5$-cyclopentadienyl)dicarbonylrhodium complexes was investigated by means of changes in C-O stretching frequencies as well as $\sp{103}$Rh NMR chemical shifts. The effect of the substituents was found to be neither a purely resonance or inductive phenomenon, but best described by a substituent parameter which took both effects into account.

No description available.

Chemicals entering the market have been steadily increasing. The Swedish Chemicals Agency is in control of the Swedish Products Register, which is storing information on chemicals  manufactured in, transferred, or imported into Sweden. Applied to the register comes the exposure index predicting exposure of chemicals. For this study, the exposure index was used to make a first prioritization of chemicals with potential of exposure to consumers, the list of suspects were further prioritized by in silico predicted physiochemical properties. Six synthetic antioxidants 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tris-tert-butyl-phenol, 2,2´-methylene-bis(4-methyl-6-tert-butylphenol), 4,4´-methylene-bis(2,6-di-tert-butylphenol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenol) propionate), were selected for target analysis. Great care to background contamination is applied since the analytes are used in everyday objects such as food package and personal care products. Human serum samples was collected from “Blodcentralen” in Stockholm, Sweden. Previous analytical methods exist for individual and combination for a few analytes but lacks in combination of all selected analytes. A previous method for the extraction without clean-up of some of the analytes in serum were tested but lacked in efficiency for all analytes, hence an clean-up step for removal of lipids were added. A gas chromatography mass spectrometry method was developed for simultaneous analysis of the six analytes. Four of the target analytes were detected and three were quantified (2,4-di-tert-butylphenol 2.20-3.33 ng/mL, 2,6-di-tert-butyl-4-methylphenol 3.22-3.93 ng/mL and 2,4,6-tris-tert-butyl-phenol 0.054-0.104 ng/mL). 2,2´-methylene-bis(4-methyl-6-tert-butylphenol) was detected in high concentration but due to linearity problems (R2<0.99) it was not quantified. To the best of my knowledge this is the first time that 2,4,6-tri-tert-butylphenol and 2,2´- methylene-bis(4-methyl-6-tert-butylphenol) have been detected in human serum.

No description available.

This thesis presents two new concepts for separation of micro particles using dielectrophoresis, demonstrated by calculated examples, as well as a new method for obtaining dielectric data on living cells. The thesis is based on four papers. Paper I describes how the trapping efficiency of micro particles may be significantly increased when superpositioned electric fields are employed in a high conductivity medium. Avoiding low conductivity media is important when working with living cells. Calculations were performed to predict trajectories of Escherichia coli bacteria in the system with superpositioned electric fields, and a model was developed which employed two arrays of interdigitated electrodes in a micro channel. Paper II proposes a new concept for separation of micro particles, based on repetitive dielectrophoretic trapping and release in a flow system. Calculations show that the resolution increases as a direct function of the number of trap and release steps, and that a difference in size will have a larger influence on the separation than a difference in dielectrophoretic properties. Polystyrene beads in deionized water were used as a model, and calculations were performed to predict the particle behavior and the separation efficiency. It should be possible to separate particles with a size difference of 0.2 % by performing 200 trap-and-release steps. The enhanced separation power of multi step dielectrophoresis could have significant applications, not only for fractionation of particles with small differences in size, but also for measuring changes in surface conductivity. Paper III presents a new calculation method for predicting dielectrophoretic motion of micro particles. The method is based on a soft sphere method often used in molecular dynamics. Results from the calculations are in good agreement with theoretical predictions as well as initial experimental results, showing that the method provides good efficiency and accuracy. Paper IV describes a new method for measurements of conductivity of living bacteria. To obtain reliable conductivity values, it is important to handle the cells as gently as possible during the measurement process. A standard conductivity meter was used in combination with cross-flow filtration. In this way, repeated centrifugation and resuspension is avoided which otherwise may cause damage to the bacteria. The conductivity of Bacillus subtilis was determined to be 7000 μS/cm by means of the cross-flow filtration method, and the values differ from earlier published values by almost an order of a magnitude. In addition to the work presented in the papers, some experimental dielectrophoresis work in chip-based systems was performed. The behavior of Escherichia coli and polystyrene beads at different voltages and frequencies were studied. Separation of beads with different sizes was achieved on an array of interdigitated electrodes. Using electrodes with a pointed shape, alignment in different directions, pearl-chain formation, rotation, and other dielectrophoretic motion of E. coli were observed. / QC 20101108

No description available.

Research concerning lignin has increased during the last years due to its renewability and ready availability in black liquor at pulp mills. Today, the kraft lignin found in black liquor is used as a fuel to gain energy in the recovery boiler at the mill. However, a new isolation concept, LignoBoost®, has enabled isolation of part of the lignin while allowing the use of black liquor as a fuel. This isolated lignin can be utilised as a fuel in, for example, thermal power stations or further upgraded to more value-added products. In this context, the most interesting value-added product is carbon fibre. The demand for carbon fibre has increased, but the biggest obstacle for a more extended use is the high production cost. About half of the production cost is related to the raw material. In this work, the possibility of using kraft lignin as a precursor for carbon fibre production has been investigated through fundamental studies. Kraft lignins originating from birch, Eucalyptus globulus, softwoods and softwoods from liner production have been studied. By separating the lignin while still in solution in the black liquor, unwanted large particles such as carbohydrates can easily be removed. After isolation according to the LignoBoost process and purification with the use of an ion-exchanger, the lignins have been both chemically and thermally characterised. Identification of the released compounds at different temperatures has been performed because only 40% of carbon relative to original lignin remains, down from theoretical 60% after thermal treatment up to 1000°C. The main released compounds were phenols, as revealed by pyrolysis-GC/MS. Additionally, a pre-oxidation was done in order to try to stabilise the lignins. It was shown that an oxidation prior to the thermal treatment increases the yield by more than 10% and that the main release of compounds takes place between 400°C and 600°C. Fractionated lignin is better qualified as raw material for carbon fibre production because it is purer and its softening temperature can be detected. Fractionated kraft lignins from all investigated wood sources have high possibilities to act as precursors for the manufacture of carbon fibre.

The high throughput capabilities of protein mass fingerprints measurements have made mass spectrometry one of the standard tools for proteomic research, such as biomarker discovery. However, the analysis of large raw data sets produced by the time-of-flight (TOF) spectrometers creates a bottleneck in the discovery process. One specific challenge is the preprocessing and identification of mass peaks corresponding to important biological molecules. The accuracy of mass assignment is another limitation when comparing mass fingerprints with databases.;We have developed an automated peak picking algorithm based on a maximum likelihood approach that effectively and efficiently detects peaks in a time-of-flight secondary ion mass spectrum. This approach produces maximum likelihood estimates of peak positions and amplitudes, and simultaneously develops estimates of the uncertainties in each of these quantities. We demonstrate that a Poisson process is involved for time-of-flight secondary ion mass spectrometry (TOF-SIMS) and the algorithm takes the character of the Poisson noise into account.;Though this peak picking algorithm was initially developed for TOF-SIMS spectra, it can be extended to other types of TOF spectra as soon as the correct noise characteristics are considered. We have developed a peak alignment procedure that aligns peaks in different spectra. This is a crucial step for multivariate analysis. Multivariate analysis is often used to distill useful information from complex spectra.;We have designed a TOF-SIMS experiment that consists of various mixtures of three bio-molecules as a model for more complicated biomarker discovery. The peak picking algorithm is applied to the collected spectra. The algorithm detects peaks in the spectra repeatably and accurately. We also show that there are patterns in the spectra of pure biomolecules samples. Furthermore, we show it is possible to infer the concentration ratios in the mixture samples by checking the strength of the patterns.