No description available.

Ion pair chromatography has found many uses within analytical chemistry and understanding of the chromatographic process with an ion-pairing reagent have been studied since the 1970s. The adsorption of the Ion-pairing reagent to the stationary phase is understood to be important and many studies have been dedicated to looking at the adsorption isotherms of the earlier quaternary alkylammonium ions. Trialkylamines have been found to have some advantages over quaternary alkylammonium ions and are almost exclusively used in the analysis of oligonucleotides. Despite this there is a lack of studies looking at the adsorption isotherms of these molecules. A method for determining the adsorption isotherm of triethylamine and tributylamine was recently published by Haseeb et al. (2023) were the adsorption isotherm of tributylamine displayed and unusual behaviour. This raised the question of how the adsorption isotherm of the ion-pairing reagent relates to the retention of the analytes, which is the topic of this project. The retention factor of a set of carboxylic and sulfonic acids were determined at increasing concentration of triethylamine and tributylamine. The retention data was used to assess the validity of the electrostatic retention model by Ståhlberg and the Extended thermodynamic approach by Cecchi, as both these models can be used to relate the adsorption to the retention factor. Results from triethylamine were harder to interpret and tributylamine subsequently became the main focus of the project. The results from tributylamine showed a clear division between carboxylic and sulfonic acids in terms of selectivity and determined surface potential. This could not be explained by the electrostatic retention model and led to the adoption of the Cecchi retention model. The adsorption isotherm of tributylamine was determined by two methods and used to fit the Cecchi model to the retention data of three analytes. This could potentially be used to interpret the adsorption isotherms influence on the retention factor, although the attained relationship should be questioned due to uncertainty in the determined adsorption isotherms.

No description available.

This ‘scouting’ work aimed to investigate the possibility of using non-aromatic monomers to prepare porous monolithic materials by utilizing varying compositions under spinodal decomposition and step polymerization. 1,3,5-Triglycidyl isocyanurate (TEPIC) was employed as a main molecular structural scaffold. Factors such as stepwise curing temperature and ratios of monomers and solvents have been explored by multi-variate experimental design and analysis. For the material characterization, specific sur-face area analysis (by the BET method) and scanning electron microscopy (SEM) were used to determine the monolith’s total surface areas, monolith morphologies, and skele-ton structures. The most promising material (NEM-15), having a specific surface area of 2.8 m2/g and 3-D skeleton, was in situ synthesized in capillary columns (I.D. 25, 50, 75, and 100 μm) for further chromatographic evaluation.

No description available.

Recent studies have discovered an increasing amount of unknown organofluorine in human blood. This increase insinuate that humans might be exposed to potentially new and unidentified organofluorine compounds. Currently there is a large gap between the amount of per- and polyfluorinated substances (PFAS) being monitored and the number of PFAS existing. Due to regulations of legacy PFAS like perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), production have shifted to new PFAS, mainly short-chains (C4-C6). New approaches have been made in order to discover these emerging PFAS, for example total oxidizable precursor (TOP) assay and extractable organofluorine (EOF) analysis. Though, these methods are non-specific and therefore useful in screening of fluorinated compounds. In today’s pharmaceutical market, a lot of drugs contain fluorine, and there is a current increase in number of fluorinated pharmaceuticals. Since EOF analysis measures all organofluorine that can be extracted, the presence of fluorinated pharmaceuticals in a sample may contribute to the EOF amount. However, if fluorinated pharmaceuticals do co-extract during sample preparation for common PFAS analysis is not yet known. This study evaluates if selected pharmaceuticals (fluoxetine, seproxetine, celecoxib and ciprofloxacin) will be co-extracted during ion pair extraction, a common extraction for EOF analysis. The extraction was first optimized in order to gain a good extraction efficiency for the pharmaceuticals. Ion pair solution adjusted to different pH’s (pH 3-4, pH 10 and pH 12) was tested, celecoxib had a good recovery independent of what pH was used (95%-102%), fluoxetine and seproxetine were only extractable at high pH’s (10 and 12) and had a recovery of around 90%, ciprofloxacin, however, could not be extracted no matter a low or high pH. The extraction was then conducted both with a pH of 10 and with a low pH (3-4) on human sera samples (n=6); the sera samples included 3 samples where subjects had been taking fluoxetine and 3 control samples. When analysis of the extracted sera samples was performed, no detectable level of pharmaceutical including its known metabolite seproxetine was found. An EOF and TF analysis of the sera samples were also performed. The EOF analysis could however not indicate any presence of pharmaceutical due to contamination in the procedural blanks. The TF analysis indicated vaguely a higher amount of total fluorine in the sera samples where subjects had taken fluoxetine compared to the control group; however, the large variation between the two groups make it hard to draw any conclusion. Since fluoxetine, seproxetine and celecoxib could be extracted when spike tests were performed, hypothetically they could contribute to the EOF amount. However, since no detectable level was found in the sera samples after extraction it cannot be stated for sure that these pharmaceuticals can be extracted from human blood, using ion-pair extraction. The unanswered question here is if the pharmaceutical is present in some other form in the sera samples, which cannot be extracted, or if it is even present at all.

Silver birch, Scots pine, and Norway spruce are the three most common types of trees in Sweden and make up to 90% of standing volume in Swedish forests (Skogsstyrelsen 2015, 3). With millions of cubic meters of wood being cut down annually, bark and other residues that cannot be used for sawn timber is left over and burnt for energy. Since bark makes up ~10-15% of harvested volume, it is a prime target for valorization and could be incorporated into preexisting procedures or used as feedstock for new processes. Bark samples obtained from the above-mentioned tree species were characterized by analyzing the chemical composition and the susceptibility to hydrothermal pretreatment and enzymatic saccharification. The study helps to understand and compare the fundamental properties of the three bark materials and determine the potential for utilization in a biorefinery context. Chemical compositional analysis of the three bark types were performed. All bark types were high in ethanol extractives (mass fraction 23.6-27.4%, dry weight). Pine and spruce bark showed similarities in chemical composition with respect to arabinan (3.5-5.2%), galactan (2.0%), glucan (18.9%), mannan (1.9%), xylan (1.8%), total lignin (33.9%) and total ash (2.7-3.7%). However, the bark of birch varied mainly in the composition of lignin and carbohydrate content, i.e., arabinan (2.5%), galactan (1.2%), glucan (8.1%), mannan (0.8%), xylan (3.3%), total lignin (50.2%) and total ash (2.0%). Hydrothermal pretreatment at a lower combined severity (CS 2.5) seems to be more efficient for birch bark than at CS 3.3. However, the bark material of the softwood species seemed to be more susceptible to enzymatic saccharification than the hardwood species. There was a clear differentiation in the chemical composition of the hardwood and softwood bark material. Birch bark was rich in ethanol extractives, total lignin or lignin-like substances, and hemicelluloses (especially xylan). Whereas pine and spruce bark has higher fractions of ash and glucan. Comparison of the effect of enzymatic hydrolysis between samples showed clear increases in glucose concentration over time for pine and spruce. However, values for birch were much lower as it was more recalcitrant

The association of DNA/RNA to mineral surfaces is an emerging field with widespread applications from biotechnological solutions to paleogenetics. Evaluating available methods to quantify adsorption will be essential to further investigate how to control and predict loading of DNA onto minerals. This study aims to test some of the available techniques for DNA quantification by investigating sorption onto Montmorillonite (Mnt) and Kaolinite (Kao) clay minerals, exchanged with different counter-cations. UV-Vis spectroscopy was successfully used in quantifying bulk DNA. Fluorescent techniques showed less reproducibility in this study but is inherently a more sensitive method demanding a more sophisticated protocol. In theory, with the right sample preparations the method can be both selective and sensitive. With pure samples and lacking a defined fluorescent protocol UV-Vis was determined to be the method of choice. To test the influence of different counter-cations, Mnt and Kao clays were washed and exchanged with Na+, K+, Ca2+, and Mg2+ and used in the DNA sorption experiments. In solutions with monovalent ions, DNA associated strongest to Kao while in solutions with divalent ions DNA associated strongest to Mnt, as quantified by the sorption coefficient Kd. Overall, the Kd values increased in the order of Na+ < K+ < Ca2+ < Mg2+ for both minerals, with the major difference between the results being the case of monovalent and divalent cations which is in agreement with previous studies. Interestingly, when confirming mineralogy of the clay samples using powder XRD, an additional first order reflection was found in samples prepared at high temperatures (<80˚C) indicating a composite material. The distance and higher temperatures required suggest single stranded DNA could be intercalated in the Na+-exchanged Mnt. Further investigations of what ionic property determines the facilitation of DNA adsorption and the suspected DNA intercalation should be conducted.

The nanolayered manganese oxide birnessite (MnO2) is a naturally occurring mineralin soils and sediments. Its ability to capture and store water within its interlayers, andits great solar absorptivity, could be a part of the solution to global water shortage.Sorbent-based atmospheric water harvesting is a potential technology to increase thewater supply in arid areas. Fundamental studies on potential sorbents, such asbirnessite, is essential for further progress. To investigate how the nanometric waterfilms in birnessite act over a range of temperatures, Fourier Transform Infraredspectroscopy was used during 21-point adsorption/desorption isotherm cycles atconstant temperatures, from 30 to 80 °C. All spectra were analyzed and interpreted inthe computational environment of Matlab. The result showed that the water bindingin birnessite is temperature dependent, and it lose as much as half of its efficiency whenincreasing the temperature from 30 to 80 °C.

In this study, we examined the effects of temperature, heat treatment which were heated in oven for an hour in 200 ℃, and solvent on the adsorption isotherm for thymol and benzoic acid on the three surfaces (modified calcium carbonate, silica gel, and perlite). For the first effect, the adsorption isotherm for benzoic acid on modified calcium carbonate was determined at temperatures of 25, 35, 45 and 55 ℃ in ethanol solvent. While for the last two effects, the adsorption isotherm for ethanol, acetonitrile, and n-heptane solutions wasdetermined at 25 ℃. UV-spectrophotometer measurements have been conducted todetermine the amount of adsorbed. The main purpose of this project is to examine the antimicrobial substances benefits which prolong food shelf life. However, it’s better to place those substances in so called food pads than to add it directly to the food. That certainly reduces the bacterial growth in the food pads. A grater amount of thymol was found to be adsorbed in n-heptane than the other solutions, additionally, a greater amount of benzoic acid was seen in ethanol than it was in acetonitrile or n-heptane. Sometimes the adsorption capacity has a large effect during heat treatment, while other times it has a small effect. The study also showed that the amount of benzoic acid adsorbed on modified calcium carbonate increases as temperature decreases