Dissertations / Theses on the topic 'Size exclusion chromatography (SEC)'
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Haider, Syed. "Enhanced gel electrophoresis (GE) and inductively coupled plasma-mass spectrometry (ICP-MS) based methods for the identification and separation of proteins and peptides." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10279.
Full textGhislain, Thierry. "Nature, origine et réactivité de la matière organique fossile dans les sols et sédiments : développements et applications de la photoionisation - spectrométrie de masse haute résolution (APPI-QTOF) et couplage avec la chromatograhie d'exclusion stérique (SEC)." Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10070/document.
Full textThe development of analytical tools for organic geochemistry analysis has increased these past years. This development has allowed answering many questions about organic matter composition. However, many issues remain to be clarified including the characterization of high molecular weight fractions and monitoring the reactivity of organic matter. This thesis has focused on both (i) existing method improvements for fossil organic geochemistry analysis but also on (ii) developing a new type of coupling between the size exclusion chromatography (SEC) and the APPI-QTOF mass spectrometry for high molecular weight weakly polar fractions. Adjustments on APPI-QTOF mass spectrometry have allowed a better understanding of polyaromatic organic contaminant reactivity in presence of mineral matrices. The success of this coupling has allowed a better understanding of the structure of asphaltenes. However despite the "simplification" obtained by the SEC, the large amount of information remains difficult to interpret and time-consuming. A mathematical model has been developed based on numerical and statistical analysis of mass spectra, allowing direct comparison of mass spectra and being able to identify several types of information such as origins of samples, monitoring of physico-chemical processes and also the efficiency of soil recovery treatments as well as the identification of analytical protocols
Kapadi, Ajith Nayak. "Size Exclusion PEGylation Reaction Chromatography Modelling." The University of Waikato, 2006. http://hdl.handle.net/10289/2504.
Full textBatas, Borislav. "Protein refolding using size exclusion chromatography." Thesis, University of Bath, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337817.
Full textPopovici, Simona-Tereza. "Towards small and fast size-exclusion chromatography." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/77409.
Full textZiebell, Angela Louise. "Modelling lignin depolymerisation using size exclusion chromatography." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/35984.
Full textPresented for full assessment for the degree of Doctor of Philosophy, Faculty of Life and Social Sciences, Swinburne University of Technology - 2008. Typescript. Bibliography: p. 222-246.
Torabi, Keivan. "Fourier transform infrared spectroscopy in size exclusion chromatography." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0002/MQ45901.pdf.
Full textBayram-Hahn, Zöfre [Verfasser]. "Inverse size exclusion chromatography (ISEC) / Zöfre Bayram-Hahn." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2007. http://d-nb.info/1230355758/34.
Full textSoponkanaporn, Teerapon. "Characterization by size exclusion chromatography of cationic polyelectrolyte degradation." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74058.
Full textRao, Baihua. "Size exclusion chromatography of polyolefins and evaluating local polydispersity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ33961.pdf.
Full textRing, Ludwig. "Purification of psychoactive biomolecules in plants using size exclusion chromatography." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-18434.
Full textSize exclusion chromatography (SEC) was applied for purification of psychoactive biomolecules from plants. These molecules are in the same molecular weight range, but do not necessarily share other chemical properties, that makes the SEC technique efficient. By applying SEC as a first purification step much of the co-extractives from the plants can easily be removed. Large amounts of target substance can be obtained with little effort if the system is automated. Combining SEC with a second purification step, consisting of normal phase chromatography, provides high purity of the target substance.
Both known and unknown psychoactive biomolecules can easily be purified using the purification method developed in this Master's Thesis. Purifications that previously required long time and much "hands-on" can be completed much faster and with less manual work.
The method developed was tested on cannabis, coffee and 'Spice' with good results.
Weatherell, Carl J. (Carl John) Carleton University Dissertation Chemistry. "The size exclusion chromatography of animal glues in zinc electrolytes." Ottawa, 1994.
Find full textBrandt, Josef. "Temperature Dependent Size Exclusion Chromatography for Investigating Thermoreversibly Bonding Polymer Systems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-207589.
Full textHolland, Daniel Joseph. "Investigations of mass transfer in size exclusion chromatography by nuclear magnetic resonance." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604160.
Full textMontenegro, Ana M. C. "Studies of column packings for polymer separations by size exclusion and interactive chromatography." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/11754.
Full textGimpl, Katharina [Verfasser], and Sandro [Akademischer Betreuer] Keller. "Triple-Detection Size-Exclusion Chromatography of Membrane Proteins / Katharina Gimpl. Betreuer: Sandro Keller." Kaiserslautern : Technische Universität Kaiserslautern, 2016. http://d-nb.info/1097263479/34.
Full textHouseman, Jonathan. "Branched chains in poly(methyl methacrylate) polymerisations incorporating a polymeric chain transfer agent." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/34854.
Full textEricsson, Victoria. "Development of a Size Exclusion Chromatography metod for analysis of extraction solutions from urinary catheters." Thesis, Uppsala University, Analytical Pharmaceutical Chemistry, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-124007.
Full textThis project focused on developing a Size Exclusion Chromatography (SEC) methodwith Refractive Index (RI) detection for analysis of extraction samples from urinarycatheters to detect compounds that can be extracted from the catheter during use.Mobile phases, extraction fluids and sample concentrations were varied, as well aspore sizes of the columns, to investigate the applicability of this technique forcharacterization of the coating and potential leachables. Analyses of extractionsamples showed that this method can be used for analyses of polyvinylpyrrolidone(PVP), which is the main component in the coating, giving rise to the specialcharacteristics of the coating. No compounds could be detected from extraction ofuncoated catheters.Comparisons were made between different raw catheter materials, PVC and POBE,and differences in molecular weight distribution of the extracted PVP compoundswere seen, in spite of identical coating processes, indicating that the bonding of PVP inthe coating depends on raw catheter material. Furthermore, radiation effects alsodiffered, where a larger decrease in high-molecular weight fractions of PVP was seenwith increasing radiation dose from extracted PVC catheters, compared to thosefrom POBE. Analyses of radiated PVP powder showed opposite radiation effects thanthose from radiated catheters; that is, a steady increase in molecular weight withincreasing radiation dose, indicating cross-linking of PVP when radiated in powderform, and consequently chain-scission of high-molecular PVP fractions when radiatedbonded to the catheter coating.The SEC-RI method was concluded to be a useful tool for qualitative analyses of thedifferences in molecular weight distribution of PVP from the different extractionsamples, but showed low reproducibility in molecular weight calculations and therelative molecular weights calculated from these analyses differed significantly fromtrue molecular weights. This method could therefore not be used to give a goodestimation of true molecular weights.
Allpike, Bradley. "Size exclusion chromatography as a tool for natural organic matter characterisation in drinking water treatment." Curtin University of Technology, Dept. of Applied Chemistry, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=18675.
Full textThese parameters included eluent composition, ionic strength of the sample, flow rate and injection volume. Firstly, it was found that increasing the ionic strength of the HPSEC eluent resulted in less exclusion of NOM from the stationary phase. Stationary phases used in HPSEC contain a residual negative charge that can repel the negatively charged regions of NOM, effectively reducing the accessible pore volume. By increasing the ionic strength, interactions between the stationary phase and eluent enabled a larger effective pore size for the NOM analytes. However, increasing ionic strength of the eluent also resulted in a loss of peak resolution for the NOM portion able to access the pore volume of the stationary phase. Determining the ideal eluent composition required the balancing of these two outcomes. Matching of the ionic strength of the sample with the eluent was also an important consideration. Retention times were slightly lower when the sample ionic strength was not matched with the eluent, especially for the lowest MW material, although the effect on chromatography was minimal. Flow rate had no effect on the resolution of the HPSEC chromatogram for the portion of material able to permeate the pore space of the stationary phase. Changes in the volume of sample injected had a marked effect on the elution profile of the NOM sample. Besides the obvious limitation of detection limit, only minor changes in elution profile were obtained up to an injection volume of 100 µL. Volumes above this value, however, resulted in significant peak broadening issues, as well as an undesirable effect on the low MW portion of detected DOC.
In Chapter 3, high pressure size exclusion chromatography with UV254 [subscript] and on-line detection of organic carbon (HPSEC-UV254[subscript]-OCD) was used to compare the removal of different apparent MW fractions of DOC by two process streams operating in parallel at the local Wanneroo groundwater treatment plant (GWTP). One of these two process streams included alum coagulation (operating in an enhanced coagulation mode (EC) for increased DOC removal) and the other stream included a magnetic ion exchange (MIEX®) process followed by alum coagulation (MIEX®-C). The MIEX® process is based on a micro-sized, macroporous, strong base anion exchange resin with magnetic properties, which has been designed to remove NOM through ion exchange of the anionic sites in NOM. Water was sampled from five key locations within these process streams, and the DOC at each location was characterised in terms of its MW distribution. HPSEC was carried out using three different on-line detector systems, namely OCD, UV absorbance detection at 254 nm, and fluorescence detection (λex[subscript]= 282 nm; λim[subscript] = 353 nm). This approach provided significant information on the chemical nature of the DOC in the various MW fractions. The MIEX®-C process was found to outperform the EC process: these two processes removed similar amounts of high and low MW DOC, but the MIEX®-C process showed greater removal of DOC from the intermediate MW fractions. The two coagulation processes (EC and coagulation following MIEX®) showed good removal of the fractions of highest MW, while the MIEX® process alone was found to remove DOC across all MW fractions.
These results seem to indicate that anionic groups, particularly susceptible to removal with MIEX® treatment, are well distributed across all MW fractions of NOM. In agreement with previous studies, MIEX®-C outperformed EC in the overall removal of DOC (MIEX®-C removed 25 % more DOC than EC). However, 70% of the additional DOC removed by MIEX®-C was comprised of a surprisingly narrow range of medium-high MW fractions. The development of a novel online organic carbon detector (OCD) for use with HPSEC for determining the MW distribution of NOM is described in Chapter 4. With UV absorbance detection, the magnitude of the signal is based on the extinction coefficient of the chromophores in the analytes being investigated; whereas the signal from an OCD is proportional to the actual organic carbon concentrations, providing significantly more information. The development of an online OCD involved the separation of analytes using HPSEC, removal of inorganic carbon species which may interfere with organic carbon determination, oxidation of the organic carbon to carbon dioxide, separation of the produced carbon dioxide from the aqueous phase and subsequent detection of the gaseous carbon dioxide. In the new instrument, following separation of components by HPSEC, the sample stream was acidified with orthophosphoric acid to a concentration of 20 mmol L-1[superscript], resulting in a pH of ≤ 2, in order to convert inorganic carbon to carbon dioxide. This acid dose was found to remove greater than 99 % of inorganic carbon once the acidified sample was passed through a hydrophobic polytetrafluoroethylene (PTFE) membrane allowing the passage of dissolved gases (under negative pressure from a vacuum pump) but restricting the flow of the mobile phase.
Several factors influenced the oxidation of the organic carbon in the next step, including the dose of persulfate, the type and intensity of UV radiation and the composition of the capillary through which the sample stream passes. Through optimisation of this process, it was found that a persulfate dose of 0.84 mmol L-1[superscript] in the sample stream was required for optimum oxidation efficiency. A medium pressure UV lamp was compared to a vacuum UV lamp for its efficiency in oxidation of organic carbon to carbon dioxide. While the medium pressure lamp produced a far smaller percentage of its total radiation at the optimum wavelength for oxidation of organic compounds, the greater overall intensity of the medium pressure lamp was shown to be superior for this application. The composition of the capillary was shown to have a considerable effect on the oxidation efficiency. A quartz capillary, internal diameter 0.6 mm, was compared with a PTFE capillary, internal diameter 0.5 mm, for the oxidation of organic carbon by external UV treatment. While peak width, an important consideration in chromatographic resolution, was greater for the larger internal diameter quartz capillary, the lower UV transparency of PTFE combined with the shorter contact time, due to the reduced internal diameter of the capillary, resulted in a less efficient oxidation step using the PTFE capillary. The quartz capillary was therefore chosen for use in the UV/persulfate oxidation step for oxidation of organic carbon to carbon dioxide. Separation of the produced carbon dioxide from the sample stream was achieved by sparging with nitrogen and contacting the gas/liquid mixture with a hydrophobic PTFE membrane, restricting the passage of the liquid while allowing the nitrogen and carbon dioxide gases to pass to the detection system.
The only factor influencing this separation was the flow of the nitrogen sparge gas, with a flow of 2 mL min-1[superscript] found to be optimum. Detection of produced carbon dioxide was via a Fourier transform infrared (FTIR) spectrometer with a Iightpipe accessory. The Iightpipe accessory was designed for use as a detector for gas chromatography and the small size of the detector cell was ideal for use with this application. Using the new system described, concentrations of a single peak could be determined with a detection limit of 31 ng and a determination limit of 68 ng. The development of the new OCD allowed characterisation of NOM in terms of its MW distribution and the UV and fluorescence spectral properties of each MW fraction. Further characterisation of MW fractions of NOM from a local groundwater bore was carried out by separation of the fractions by preparative HPSEC, followed by off-line analysis. Preparative HPSEC involved the injection of a pre-concentrated groundwater sample multiple times, using a large scale HPSEC column, then collecting and combining material of identical MW. This allowed each MW fraction of the sample to be further characterised as described in Chapter 5. Preparative HPSEC has only previously been applied to a small number of samples for the concentration and fractionation of NOM, where the structural features of the various MW fractions were studied. In the current research, more extensive studies of not only the chemical characteristics, but also the disinfection behaviour, of the MW fractions were conducted. Separation of the sample was conducted on a large diameter silica-based HPSEC column, with fraction collection based on semi-resolved peaks of the HPSEC chromatogram. Nine MW fractions were collected by this method.
After concentration and dialysis to remove the buffer salts in the HPSEC mobile phase, each fraction was re-analysed by analytical HPSEC-UV254[subscript] and showed a single Gaussian shaped peak, indicating discrete MW fractions had successfully been collected. Analysis of the collected MW fractions indicated that 57 % of the organic carbon was in Fractions 3 and 4, with 41 % in Fractions 5-9, leaving only 2 % in Fractions 1 (highest MW) and 2. For each of the nine MW fractions, chorine demand and 7 day trihalomethane formation potential (THMFP) were measured on dilute solutions of the same DOC concentration, and solid state 13[superscript]C NMR spectra were recorded on some of the solid isolates obtained after Iyophilisation of the separate or combined dialysis retentates. The larger MW Fractions 3 and 4 were found to contain a greater proportion of aromatic and carbonyl carbon, and the lower MW Fractions 5 and 6 and Fractions 7-9 contained greater proportions of aliphatic and O-aliphatic carbon, by this technique. Chlorine demand experiments on each individual fraction with a normalised DOC concentration indicated that the largest MW fraction (Fraction 1) had the lowest chlorine demand. It was concluded that material in this fraction may be associated with inorganic colloids and unavailable for reaction with chlorine. Fraction 3 had the highest chlorine demand, just over two times more than the next highest chlorine demand (Fraction 4) and approximately three times the chlorine demand of Fraction 2. The organic material in Fraction 2 was postulated to contain a mixture of the reactive material present in Fraction 3 and the colloidal associated material present in Fraction 1.
NMR analysis indicated that the difference between Fraction 3 and Fraction 4 was a reduction in reactive aromatic carbon and hence the lower chlorine demand in the latter fraction. Fractions 5-8 had similar chlorine demands, lower than Fraction 4, while Fraction 9 had a very low chlorine demand similar to that of Fraction 1. For Fractions 5-9, the lower aromatic carbon content most likely resulted in the lower chlorine demand. The 7 day THMFP experiments showed some clear trends, with Fraction 1 and Fraction 2 producing the least amounts of THMs but having the greatest incorporation of bromine. Fractions 3 and 4 produced the greatest concentration of THMs with the lowest bromine incorporation, perhaps as they contained fast reacting THM precursors and the higher chlorine concentrations resulted in greater amounts of chlorinated THMs. Fraction 5 and Fraction 6 produced similar levels of THMs over 7 days to Fractions 7-9 (approximately 75% of the amount formed by Fractions 3 and 4), however, Fractions 7-9 formed these THMs more quickly than Fractions 5 and 6, with slightly greater amounts of bromine incorporation. It was thought that the increased speed of formation was due to the smaller MW of these fractions and a simpler reaction pathway from starting material to formation of THMs, as well as some structural differences. This research marks the first report of significantly resolved MW fractions being isolated and their behaviour in the presence of a disinfectant being determined. While the high MW fractions had the greatest chlorine demands and THMFPs, these fractions are also the easiest to remove during coagulation water treatment processes, as shown in Chapter 3. The lowest MW material formed significant amounts of THMs, and also formed THMs more quickly than other MW fractions.
This has important implications from a water treatment perspective, as the lowest MW material is also the most difficult to remove during conventional treatment processes. Solid samples of NOM were isolated from water samples taken from four points at the Wanneroo GWTP using ultrafiltration and subsequent Iyophilisation of the retained fractions, as described in Chapter 6. The sampling points were following aeration (Raw), following treatment by MIEX®, following treatment by MIEX®-C and following treatment by EC. Elemental analysis, FTIR spectroscopy, solid state 13[superscript]C NMR spectroscopy and HPSEC-UV254[subscript]-0CD analysis were used to compare the four isolates. Treatment with MIEX®-C was found to remove the greatest amount of NOM. Additionally, treatment with MIEX®-C was able to remove the largest MW range of NOM, with the remaining material being depleted in aromatic species and having a greater proportion of aliphatic and O-aliphatic carbon. EC treatment completely removed the NOM components above 5000 Da, but NOM below this was not well removed. NOM remaining after the EC train had a lower aromatic content and more aliphatic oxygenated organic matter than the RW. The remaining organic matter after MIEX® treatment contained less aromatic material compared to the RW, but had a greater aromatic content than either of the EC or MIEX®-C samples. HPSEC was a significant analytical technique used throughout this research. Initial optimisation of an HPSEC method was an important development which allowed improved resolution of various MW fractions. The application of this technique and comparison of three detection systems for the study of DOC removal showed, for the first time, the performance of MIEX® treatment at a full scale groundwater treatment facility.
The use of various HPSEC detection systems allowed significant characterisation of the MW fractions, more information than had previously been gathered from such a sample set. This work demonstrated the need for OCD when applying HPSEC to the study of NOM. As such, a system was constructed that built on previously developed systems, with the use of a small detector cell enabling detection limits capable of measuring even the most dilute natural and treated water samples. To study the individual MW fractions in detail, preparative HPSEC was applied and, for the first time, the disinfection behaviour of various MW fractions was examined. Interestingly, the lowest MW fractions, acknowledged to be the most recalcitrant to conventional water treatment processes, produced significant quantities of THMs. Also the formation kinetics of THMs from the low MW fractions indicated that THMs were formed as quickly as, or perhaps even at faster rates than from the larger MW fractions. Finally, structural characterisation of NOM at four stages of the Wanneroo GWTP indicated MIEX®-C treatment was superior to EC, of significant interest for the water industry.
Heldreth, Lori G. "The evaluation of crosslinked poly-4-vinylpyridine as a packing material for size exclusion chromatography." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/44471.
Full textMaster of Science
Tongdang, Taewee. "Molecular structure of native and processed rices." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368246.
Full textSjöholm, Elisabeth. "Characterisation of kraft pulps by size-exclusion chromatography and kraft lignin samples by capillary zone electrophoresis." Doctoral thesis, KTH, Pulp and Paper Technology, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2846.
Full textIn the present thesis two analytical methods forcharacterisation of underivatised pulp and lignin samplesobtained from kraft pulping of hardwood and softwood areevaluated. The first method is the use of lithiumchloride/N,N-dimethylacetamide (LiCl/DMAc) for dissolution andsize-exclusion chromatography (SEC) of pulps. The applicabilityof LiCl/DMAc-SEC is demonstrated for birch wood kraft pulpswith different relations between zero-span tensile strength andviscosity. The second method concerns the applicability ofcapillary zone electrophoresis (CZE) for characterising blackliquor and isolated lignin samples with respect to mobility,i.echarge density. A method for determining the averagemobility (µav) of the mobility distributions to easecomparison between samples is also presented.
The solubility in LiCl/DMAc and the elution behaviour in SECdiffer between hardwood and softwood kraft pulps. Hardwoodkraft pulps are completely dissolved in LiCl/DMAc, whereas highamounts of lignin and presence of glucomannan restrict thesolubility of softwood kraft pulps. The undissolved fraction ofsoftwood kraft pulps consists of larger amounts of mannose andlignin but has a diminished xylose content compared with theinitial pulp. Xylan and cellulose of hardwood kraft pulps arefairly well separated by LiCl/DMAc-SEC. In contrast, themolecular weight distributions (MWD) of softwood kraft pulpsare more complex. It was found that the hemicelluloses ofsoftwood pulps elute over the entire molecular weight range,indicating various degrees of association with cellulose. Theneutral monosaccharide composition implies that associationsbetween galactoglucomannan and cellulose increase withdecreasing amount of galactose. The elution behaviour ofsoftwood kraft pulp xylan suggests that this xylan consist ofsubstructures with varying propensity for associating withcellulose and/or mannan. In absence of associations betweencellulose and hemicellulose, cellulosic solutions of LiCl/DMAcconsist of cellulose aggregates, which is seen as a shoulder onthe high molecular weight end of the MWD of cellulose.According to the profiles of the MWD and light scatteringmeasurements, it is possible to break these aggregates bymechanical treatment of the solutions, without causing severecleavage of the glycosidic bonds. The relation between MWD andzero-span tensile strength was studied on hardwood kraft pulpsdegraded by gamma irradiation, oxygen/alkali or alkali. For alltreatments, the MWD of cellulose is shifted to a lowermolecular weight range as degradation proceeds. In thechemically treated pulps, a shoulder on the lowmolecular-weight end of the cellulose distribution graduallydevelops, which is not seen for the gamma treated pulps. Theobserved decrease in shape factor/fibre strength of thechemically treated-pulps is proposed to be due to a combinationof heterogeneous degradation and removal of hemicellulosewhereas the decrease in Mw of cellulose is of minorimportance.
The mobility distributions obtained by CZE differ betweenblack liquor, isolated dissolved lignin and isolated residuallignin. The µav measured at pH 12 reveals that theresidual lignin isolated from pine wood kraft pulp has asignificantly lower charge density than the lignin removed fromthe pulp throughout the cook. At the end of the kraft cook ofbirch, the µav of the isolated residual lignin is aboutthe same as that of the isolated dissolved lignin, whichsuggests that the solubility is sufficient for the pulp ligninto be dissolved. Comparisons between the µav at pH 12 andpH 10 indicate that the isolated dissolved lignin samplesobtained in the middle of the cook have a lower acidity thanthe other samples. The observed difference in µav betweenblack liquor and isolated dissolved lignin may be due toassociations between lignin fragments and carbohydrate polymersin the black liquor.
Keywords:Kraft pulps, Black liquor, Cellulose,Hemicellulose, Lignin, LiCl/DMAc, Dimethylacetamide,Size-exclusion chromatography, Capillary zoneelectrophoresis
Fahey, Edward Michael. "A study of the refolding of urokinase plasminogen activator by size exclusion chromatography and batch dilution." Thesis, University of Bath, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323582.
Full textBotha, Carlo Bennet [Verfasser], and M. [Akademischer Betreuer] Wilhelm. "Method Development of New Chemically Sensitive Detectors for Size Exclusion Chromatography / Carlo Bennet Botha ; Betreuer: M. Wilhelm." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1230475826/34.
Full textCoromili, Vaia. "Permeability of alginate polylysine microcapsules encapsulating hepatocytes as a biohybird artificial liver by high performance size exclusion chromatography." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37662.
Full textDosanjh, J. K. S. "Protein damage during purification : understanding the effects of size exclusion chromatography on the structure of biosynthetic human insulin (BHI)." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1331879/.
Full textGilbert, Max [Verfasser], and Waltraud [Akademischer Betreuer] Schulze. "Prediction of protein-protein complexes by combining size exclusion chromatography and mass spectrometric analysis / Max Gilbert ; Betreuer: Waltraud Schulze." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2021. http://nbn-resolving.de/urn:nbn:de:bsz:100-opus-19403.
Full textDupont, Anne-Laurence. "Gelatine sizing of paper and its impact on the degradation of cellulose during aging a study using size-exclusion chromatography /." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/68918.
Full textBarnes, Suzanne R. "Size Exclusion Chromatography of Poly(2-ethyl-2-oxazoline) Homopolymers and Poly(ethylene oxide)-b-Poly(2-ethyl-2-oxazoline) Copolymers." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/24907.
Full textMaster of Science
Borgerding, Erika Michelle. "Synthesis, Molecular Weight Characterization and Structure-Property Relationships of Ammonium Ionenes." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35613.
Full textMaster of Science
Brandt, Josef [Verfasser], Brigitte [Akademischer Betreuer] [Gutachter] Voit, Albena [Akademischer Betreuer] Lederer, and Peter [Gutachter] Schoenmakers. "Temperature Dependent Size Exclusion Chromatography for Investigating Thermoreversibly Bonding Polymer Systems / Josef Brandt ; Gutachter: Brigitte Voit, Peter Schoenmakers ; Brigitte Voit, Albena Lederer." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://d-nb.info/1114067814/34.
Full textWolpers, Arne. "Advances in chain-growth control and analysis of polymer: boosting iodine-mediated polymerizations and mastering band-broadening effects in size-exclusion chromatography." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://hdl.handle.net/11858/00-1735-0000-0023-9654-7.
Full textHeidenreich, Andrew J. "Synthesis and Characterization of Arborescent (Dendritic) Polystyrenes Prepared by Raft Polymerization." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1310763577.
Full textLi, Yun. "Development of Biocompatible Polymer Monoliths for the Analysis of Proteins and Peptides." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3161.pdf.
Full textNiemiec, Moritz Sebastian. "Human copper ion transfer : from metal chaperone to target transporter domain." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-100511.
Full textCelebi, Oguzhan. "Synthesis and Characterization of Poly(2-Ethyl-2-Oxazoline) Functional Prepolymers and Block Copolymers." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/24908.
Full textPh. D.
Berggren, Rickard. "Cellulose degradation in pulp fibers studied as changes in molar mass distributions." Doctoral thesis, KTH, Fibre and Polymer Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3499.
Full textIn this thesis, size-exclusion chromatography (SEC) of woodpolymers dissolved in lithium chloride/N,N-dimethylacetamide(LiCl/DMAc) has been used to characterize the molar massdistributions (MMD) of wood polymers in pulp fibers afterchemical degradation.
Characterization of birch kraft pulps subjected to ozonedegradation and acid hydrolysis, respectively, rendereddifferent changes in the MMD. Ozone degradation resulted inlarge redistributions of the original MMD, observed as thedevelopment of a distinct fraction of cellulose withintermediate molar mass. Acid hydrolysis resulted in minorchanges of the original MMD compared to ozonation. Fiberssubjected to acid hydrolysis were considerably weaker thanozonated fibers. These results indicated that there aredifferences in how the two chemicals degrade the fiber.
The solubility of softwood kraft pulp fibers was enhanced byderivatization of the fiber polymers with ethyl-isocyanateduring simultaneous dissolution in LiCl/DMAc. Thederivatization made it possible to achieve reliable estimationsof the MMD, and hence molar masses, of softwood kraft pulps.The derivatization procedure made it possible to dissolve 90 %of softwood kraft pulps with kappa numbers over 50.
Severe alkaline degradation of birch and Norway spruce woodchips was studied both by varying the pulping time and byvarying the initial alkali concentration. Differences werefound in the MMD of the two fiber types, and the alkalinedegradation was found to affect polymers in the entire MMD.
Multi-angular laser light scattering (MALLS) was used as adetection technique with SEC on cellulosic samples. The MMD andaverage molar masses obtained through directstandardcalibration with commercial standards were compared with MMDand molar masses as obtained by MALLS-detection. Largediscrepancies were found, and two methods of correcting forthese discrepancies were developed.
Theoretical simulations of polymer degradation wereperformed. Random, or homogeneous degradation was used as amodel for alkaline cellulose chain scission, and a resemblancewith experimental data was observed. End-wise depolymerizationof cellulose was also simulated and the results are discussedin the light of experimentally observed MMD.
Keywords:cellulose, kraft pulp, birch, spruce,ozonation, acid hydrolysis, degradation, MMD, sizeexclusionchromatography, light scattering, molar mass, chainscission
Aquino, Francisco Wendel Batista de. "Dextranas em açúcares e em aguardentes de cana." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/75/75132/tde-12112009-145612/.
Full textBrazil is the largest producer and exporter of sugar in the world, and the cachaça is the third most produced distilled beverage in the world. However, these products have their quality affected by the presence of dextrans. Because of its origin (a secondary compound of bacterial metabolism) and due to its physical-chemical properties, the dextrans are an important indicator to assess the sugar quality. Dextrans can lead to problems in processed food production, and it has a strong relation with insoluble deposits in sugared sugar cane spirits. The dextran molecular mass distribution profile in terms of Mn, Mw Mz and polydispersity in Brazilian sugars are reported for the first time. The analyses were accomplished by Size-exclusion chromatography, using a refraction index detector. In most of the sugar samples, it was possible to identify two major groups of dextrans with Mw averages of 5.0 x 106 e 4.8 x 104 Da. A third group of dextrans with Mw of 105 was occasionally observed. With this data, model systems were built to assess the influence of the temperature, acidity, presence metalic ions CuII, FeIII, CaII, and MgII, light incidence in relation of dextran precipitation velocities. It is demonstrated that factors temperature and acidity are the most influential in the dextran precipitation velocity in sugar cane spirits.
Zimmermann, Estevan Sonego. "Validação de método cromatográfico por exclusão molecular para avaliação de interferon-alfa2a e estudos de correlação." Universidade Federal de Santa Maria, 2010. http://repositorio.ufsm.br/handle/1/5931.
Full textHuman interferon-α2a (hIFN-α2a) is a natural protein produced by the cells of the immune system with antiviral, antiproliferative and immunomodulatory properties. A size exclusion liquid chromatography (SE-LC) method was validated for the determination of recombinant interferon-α2a (rhIFN-α2a) in pharmaceutical formulations without human serum albumin. The SE-LC method was carried out on a BioSep-SEC-S 2000 column (300 mm x 7.8 mm i.d.) maintained at 25°C. The mobile phase consisted of 0.001 M monobasic potassium phosphate, 0.008 M sodium phosphate dibasic and 0.2 M sodium chloride buffer, pH 7.4, run at a gradiente flow rate and using photodiode array (PDA) detection at 214 nm. The chromatographic separation was achieved with retention time of 17.2 min, and was linear over the concentration range of 0.5-50 MUI/mL (r2 = 0.9996). The accuracy was 101.39% with bias lower than 1.67%. The limits of detection and quantitation were 0.22 and 0.5 MIU/mL, respectively, and the method validation demonstrated acceptable results for precision and robustness. The proposed method was applied for the analysis of rhIFN-α2a in pharmaceutical dosage forms, and the content/potencies correlated to the previously validated reversed-phase (RP-LC), and the in vitro bioassay. The pharmaceutical samples were analyzed by the chromatographic methods and compared to the bioassay, showing mean differences between the estimated potency of 1.50% higher for SE-LC, and 2.45% lower for the RP-LC. The alternative methods studies contribute to improve the quality control, assuring the therapeutic efficacy of the biological medicine. Moreover, the pharmacokinetic parameters of the formulations A and B were evaluated by subcutaneous injection in rats, showing comparable profiles with Cmax of 7924.60 and 8698.68 pg/mL, respectively, and Tmax= 60 min.
O interferon-α2a humano (hIFN-α2a) é uma proteína produzida pelas células do sistema imune com propriedades imunomoduladora, antiviral e antiproliferativa. No presente trabalho, foi validado método por cromatografia líquida por exclusão molecular (CL-EM), para determinação de interferon-α2a recombinante (rhIFN-α2a) em formulações farmacêuticas sem albumina. O método CL-EM foi validado empregando coluna BioSep-SEC-2000 S (300 mm x 7,8 mm d.i.) mantida a temperatura de 25°C. A fase móvel foi composta de tampão fosfato de potássio monobásico 0,001 M, fosfato de sódio dibásico 0,008 M e cloreto de sódio 0,2 M, pH 7,4, eluída em gradiente de fluxo e utilizando arranjo de diodos (DAD) com detecção em 214 nm. A separação cromatográfica foi alcançada com o tempo de retenção de 17,2 min e o método foi linear no intervalo de concentração de 0,5-50 MUI/mL (r2 = 0,9996). A exatidão média foi de 101,39%, com erro calculado inferior a 1,67%. Os limites de detecção e quantificação foram de 0,22 e 0,5 MUI/mL, respectivamente e a validação demonstrou parâmetros aceitáveis de precisão e robustez. O método proposto foi aplicado para análise de formulação farmacêutica de rhINF-α2a e os teores/potências correlacionados com aqueles fornecidos pelos métodos previamente validados por CL-FR e bioensaio in vitro. Estabeleceu-se correlação entre os métodos, demonstrando que os biofármacos comerciais apresentaram diferenças entre as médias 1,5% maiores para o CL-EM, e 2,45% menores para CL-FR, em relação ao bioensaio. Assim, contribuiu-se para estabelecer alternativas que aprimoram o controle de qualidade, assegurando a eficácia terapêutica do produto biológico. Além disso, avaliaram-se os parâmetros farmacocinéticos das formulações A e B após injeção subcutânea em ratos, demonstrando perfis comparáveis com Cmax de 7924,60 e 8698,68 pg/mL, respectivamente, e Tmax= 60 min.
Chiang, Cheng Ching Kurt. "Natural Rubber Biosynthesis: Perspectives from Polymer Chemistry." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1386367354.
Full textMcAdams, Brandon C. "Relationships between reduced sulfur and dissolved organic matter in prairie pothole wetlands." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1493627284045985.
Full textWolpers, Arne [Verfasser], Philipp [Akademischer Betreuer] Vana, Michael [Akademischer Betreuer] Buback, and Gregory T. [Akademischer Betreuer] Russell. "Advances in chain-growth control and analysis of polymer: boosting iodine-mediated polymerizations and mastering band-broadening effects in size-exclusion chromatography / Arne Wolpers. Betreuer: Philipp Vana. Gutachter: Philipp Vana ; Michael Buback ; Gregory T. Russell." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1078150702/34.
Full textWolpers, Arne Verfasser], Philipp [Akademischer Betreuer] Vana, Michael [Akademischer Betreuer] [Buback, and Gregory T. [Akademischer Betreuer] Russell. "Advances in chain-growth control and analysis of polymer: boosting iodine-mediated polymerizations and mastering band-broadening effects in size-exclusion chromatography / Arne Wolpers. Betreuer: Philipp Vana. Gutachter: Philipp Vana ; Michael Buback ; Gregory T. Russell." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://nbn-resolving.de/urn:nbn:de:gbv:7-11858/00-1735-0000-0023-9654-7-9.
Full textFukuda, Jun. "Studies on development of analytical methods to quantify protein aggregates and prediction of soluble/insoluble aggregate-formation." Kyoto University, 2015. http://hdl.handle.net/2433/199349.
Full text0048
新制・課程博士
博士(農学)
甲第19025号
農博第2103号
新制||農||1030(附属図書館)
学位論文||H27||N4907(農学部図書室)
31976
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 加納 健司, 教授 植田 和光, 教授 植田 充美
学位規則第4条第1項該当
Gu, Binghe. "Development of Polymer Monoliths for the Analysis of Peptides and Proteins." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1296.
Full textSilva, Lucélia Magalhães da. "DESENVOLVIMENTO E VALIDAÇÃO DE MÉTODOS CROMATOGRÁFICOS PARA AVALIAÇÃO DE INTERFERON-ALFA 2a EM FORMULAÇÕES FARMACÊUTICAS." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/5904.
Full textThe interferon is a cytokine with antiviral, antiproliferative, and immunomodulatory properties. It is a protein synthesized by cells in response to viral infection, producing successive biochemistry alterations. The chromatographic methods for evaluation of recombinant interferon-alfa 2a (rhIFN-α2a) in pharmaceutical products were validated in the present work. The reversed-phase liquid chromatography method (RP-LC) was developed and validated using a Jupiter C4 column (250 mm x 4.6 mm), maintained at ambient temperature (25°C). The mobile phase A consisted of 0.1% trifluoroacetic acid (TFA) and mobile phase B consisted of 0.1% TFA in acetonitrile, run in gradient: 0.01 1 min, 38% of B; 1 5 min, 38 43% of B; 5.01 20 min, 43 45% of B; 20.01 30 min, 45 48% of B; 30.01 40 min linear back to 38% of B and 40 42 min, 38% of B. The flow rate used was 1 mL/min with detection at 214 nm. The chromatographic separation was obtained within 42 min and it was linear in the concentration range of 0.5 50 MIU/mL (r2=0.9999). The size exclusion method was developed and validated using a BioSep-SEC-S 2000 (300 mm x 7.8 mm), maintained at ambient temperature (25°C). The mobile phase consisted of 1mM potassium phosphate monobasic, 8mM sodium phosphate dibasic and 200mM sodium chloride buffer, pH 7.4, run at a gradient flow rate: 0.01 20 min, 0.5 mL/min; 20 25 min, 0.5 1.7 mL/min; 25 35 min, 1.7 mL/min; 35 38 min, 1.7 0.5 mL/min; 38 40 min, 0.5 mL/min. The method was linear in the concentration range of 0.5 - 50 MIU/mL (r2=0.9996). The procedures were validated by the parameters of specificity, linearity, precision, accuracy, robustness, limit of quantitation and limit of detection. The methods were applied for the evaluation of the rhIFN-α2a in pharmaceutical products, contributing for the establishment of alternatives which improve the quality control, assuring the safety and therapeutic efficacy of the biological product.
O interferon é uma citocina que possui ação antiviral, imunomoduladora e antiproliferativa. É uma proteína sintetizada pelas células em resposta a infecção viral, gerando sucessivas alterações bioquímicas. No presente trabalho foram validados métodos cromatográficos para a avaliação de interferon-alfa 2a (rhIFN-α2a) em produtos farmacêuticos. O método por cromatografia líquida em fase reversa (CL-FR) foi desenvolvido e validado empregando coluna Júpiter C4 (250 mm x 4,6 mm), mantida a temperatura ambiente (25°C). A fase móvel A foi composta de ácido trifluoracético 0,1% e a fase móvel B de ácido trifluoracético 0,1% em acetonitrila, eluídas no gradiente: 0,01 1 min, 38% de B; 1 5 min, 38 43% de B; 5,01 20 min, 43 45% de B; 20,01 30 min, 45 48% de B; 30,01 40 min, 48 38% de B, mantendo-se nesta proporção até 42 min. Utilizou-se vazão de 1 mL/min e detecção no ultravioleta a 214 nm. A separação cromatográfica foi obtida no tempo de 42 min, sendo linear na faixa de concentração de 0,5 - 50 MUI/mL (r2=0,9999). Paralelamente, desenvolveu-se e validou-se método cromatográfico por exclusão molecular (CL-EM) empregando coluna BioSep-SECS 2000 (300 mm x 7,8 mm), mantida a temperatura ambiente (25°C). A fase móvel foi composta de tampão fosfato de potássio monobásico 1mM, fosfato de sódio dibásico 8mM e cloreto de sódio 200mM, pH 7,4, eluída no gradiente de fluxo: 0,01 20 min, 0,5 mL/min; 20 25 min, 0,5 1,7 mL/min; 25 35 min, 1,7 mL/min; 35 38 min, 1,7 0,5 mL/min; 38 40 min, 0,5 mL/min. O método foi linear na faixa de concentração de 0,5 - 50 MUI/mL (r2=0,9996). Ambos os procedimentos foram validados com base nos parâmetros de especificidade, linearidade, precisão, exatidão, robustez, limite de quantificação e detecção. Os métodos foram aplicados para avaliação de rhIFN-α2a em produtos farmacêuticos, contribuindo para o estabelecimento de alternativas que aprimoram o controle da qualidade, garantindo a segurança e eficácia terapêutica do produto biológico.
Rebiere, Jérémy. "Nouvelle méthodologie pour la caractérisation de distributions de masses molaires d'échantillons cellulosiques complexes." Thesis, Toulouse, INPT, 2017. http://www.theses.fr/2017INPT0017/document.
Full textCellulose is a very abundant natural biopolymer. According to its origin and to its extraction mode, it presents various cristallinity rate and molar mass. Its organization relies mainly on intermolecular hydrogen bonds that form a strong network and thus limitating cellulose solubility. Complete andnon-degradative dissolution is then complicated and depends on the solvent ability to disrupt these hydrogen bonds. Analysis of the molar mass distribution (MMD) of cellulose by size exclusion chromatography (SEC) of cellulose is consequently problematic while the study of the evolution of cellulose molar mass during transformations could be extremely useful in many processes. The most common solvent used in SEC is lithium chloride/N,N-dimethylacetamide (LiCl/DMAc), which is extremely toxic. The aim of this PhD study is then to develop a new analytical method to characterize cellulose MMD using safer solvents and adapted to all kinds of cellulosic sample. Among the numerous non-derivatizing solvent systems described in the literature, three of themhave been selected. Greener and less toxic than LiCl/DMAc, their ability to dissolve cellulosic sample of various cristallinity and average molar mass without degradation was then tested. Thermogravimetric analyses and viscosimetric studies allowed to evaluate and to compare the modifications involved by the dissolution for four different cellulosic samples. LiCl/DMAc degraded the samples of higher molar mass (-cellulose and Vitacel) decreasing their degree ofpolymerization by 50 % after dissolution. Tetrabutylammonium/dimethylsulfoxide (TBAF/DMSO) system allows rapid dissolution of the 4 cellulose samples, without major degradation or modification. TBAF/DMSO system was then studied as solvent for SEC analysis of these cellulose samples. Due to the interactions between the aromatic groups composing the stationary phase with TBAF molecules, the complete system could not be used as eluant. Chosen eluant was then DMSO alone. However, as the TBAF molecules are mandatory for the dissolution of cellulose, TBAF concentration was adapted according to the cellulose nature for the preparation of the samples. For low molar mass cellulose samples, a TBAF concentration of 1 %(w/v) was sufficient and allowed to performed correctly the chromatographic analysis. For the samples of higher molar mass, this concentration was not high enough to complete the dissolution. Using, higher concentrations caused aggregation phenomena resulting in the elution of a large amount of the macromolecules in the dead volume, as observed with the analysis of pullulan standards
Schmitt, Charlène Eva. "Caractérisation de polyacrylamide de hautes masses molaires par fractionnement couplage flux force couplée à la diffusion de la lumière." Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3039.
Full textOne method for optimizing the production of hydrocarbon is based on the injection of water, viscosified by the addition of polymers such as polyacrylamides, in order to enhance the oil extraction (EOR). The viscosifying properties of polymers depend on their molecular masses. The aim of this thesis was therefore to develop new methods for determining wide molecular mass distributions and high dispersity, which are specific characteristics of samples of industrial interest in the oil sector. The analytical strategy used is based on size exclusion chromatography (SEC) and flow field flow fractionation (A4F), coupled to light scattering and refractometer. Model polymers were synthesized by a polymerization process by reversible addition fragmentation chain transfer (RAFT/MADIX). This allowed to obtain polymers in a range of molar masses between 103 and 107 g / mol and with a dispersity lower than 1.4. Through the use of these polymers, the capabilities and limitations of the two separation methods invested were evaluated. The A4F operating conditions were determined and this method has proved to be adapted to the analysis of industrial polymers distributed over 3 decades of molecular masses. Beyond the dimensional analysis, A4F-based coupling also allowed conformational analysis
Rosa, Wesley de Oliveira. "Síntese e caracterização de géis para cromatografia de exclusão por tamanho via reticulação de Acetato de Celulose com 4,4' - Difenilmetano Diisocianato (MDI)." Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8327.
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The need to obtain biomaterials in order to reduce environmental impacts has been the focus of research groups in recent years, and cellulose, a dominant component at most forms of plants is a promising resource because of its abundance. In order to improve the ability processing, the chemical modification of cellulose has been widely studied. Among the most important reactions of cellulose are: etherification, esterification, acetylation and oxidation; being cellulose acetate, viscose, nitrocellulose and cellulose ethers, the main cellulose derivatives. The chemical modification with isocyanates presents some unique properties, such as absence of by-products and chemical stability of the urethane group. In this work we were synthesized gels obtained by modified cellulose acetate (CA) with a degree of substitution (DS) 2,5 by crosslinking, with 4,4' - Diphenylmethane diisocyanate (MDI) in stoichiometry of 1:1, in homogeneous by varying the humidity and the homogenization time. For characterization were used the following techniques and tests: vibrational infrared absorption spectroscopy (Fourier Transform Spectrometer - FTIR), size exclusion Chromatography (SEC), molecular absorption spectrophotometry UV-VIS, density determining of the gels by pycnometry, determination of the coefficient swelling, determination of cross-links by Flory-Rehner theory, thermogravimetry (TG) and scanning electron microscopy (SEM). Crosslink density results showed that the gel synthesized in the absence of moisture suffered greater crosslinking with an average number of repeat units between the crosslinking points of about 1000 times lower. The potential applications of these gels were tested, by using than as stationary phase in size exclusion chromatography, having been assessed its efficiency in the fractionation and separation of natural and synthetic polymers. Results showed the effectiveness of the gel as stationary phase on separation of polymers, opening up a range of opportunities, taking into consideration the simplicity of the process and lower costs attributed to it.
A necessidade de se obter biomateriais na tentativa de reduzir impactos ambientais tem sido o foco de grupos de pesquisa nos últimos anos e, a celulose, um componente dominante na maioria das formas de plantas, é um recurso promissor devido à sua abundância. A fim de melhorar a capacidade de processamento, a modificação química da celulose tem sido amplamente estudada. Dentre as reações mais importantes da celulose estão: eterificação, esterificação, acetilação e oxidação; sendo o acetato de celulose, viscose, nitrocelulose e éteres de celulose, os principais derivados da celulose. A modificação química com isocianatos apresenta algumas propriedades únicas, como ausência de produtos secundários e estabilidade química do grupo uretano. Nesse trabalho foram sintetizados géis obtidos por meio da modificação de Acetato de Celulose (AC) com grau de substituição (GS) 2,5 através da reticulação com 4,4' - Difenilmetano Diisocianato (MDI), na estequiometria 1:1, em meio homogêneo, variando a umidade e o tempo de homogenização. Para caracterização foram utilizadas as seguintes técnicas e ensaios: espectroscopia vibracional de absorção no infravermelho por Transformada de Fourier (FTIR), cromatografia de exclusão por tamanho (SEC), espectrofotometria de absorção molecular UV-VIS, determinação de densidade dos géis por picnometria, determinação do coeficiente de intumescimento, determinação de ligações cruzadas pela teoria de Flory-Rehner, termogravimetria (TG) e microscopia eletrônica de varredura (MEV). Resultados da densidade de ligações cruzadas mostraram que o gel sintetizado na ausência de umidade sofreu uma maior reticulação, com um número médio de unidades de repetição entre os pontos de reticulação cerca de 1000 vezes menor. As aplicações potenciais desses géis foram testadas como fase estacionária em cromatografia de exclusão por tamanho, tendo sido avaliada sua eficiência no fracionamento e separação de polímeros naturais e sintéticos. Resultados mostraram a eficácia do gel como fase estacionária na separação de polímeros, abrindo uma gama de oportunidades, levando-se em consideração a simplicidade do processo e os baixos custos a ele atribuídos.
Barakat, Fatima. "Développement de méthodes analytiques pour l’analyse d’oligonucléotides thérapeutiques bio-conjugués à des lipides." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0292.
Full textAntisense oligonucleotides (ASO) have the ability to inhibit or modulate the expression of a target gene by various mechanisms. Bioconjugation of ASO with a lipid is a very promising approach which has shown an improvement in the delivery of the antisense sequence and therefore, in the therapeutic efficacy of the oligonucleotide. These new therapeutic agents, lipid oligonucleotides (LON), are amphiphilic molecules and are able to self-assemble to form supramolecular objects. Their pharmaceutical development requires suitable analytical methods to study the purity of the LONs synthesized and to be able to quantify them in the formulations but also to characterize the supramolecular assemblies formed.In this work, different methods were investigated in ion-pairing reversed-phase HPLC and hydrophilic interaction chromatography, capillary electrophoresis (CE) and size exclusion chromatography (SEC) for LON analysis with various chemical structures. Despite the different parameters studied, the asymmetry of the peaks obtained by HPLC limits its use for assays. On the other hand, a quantitative method has been developed and validated in CE in the presence of cyclodextrins (CD). The complexation constant between free LON and CDs as well as the electrophoretic mobility of the complex were determined. Finally, the potential of SEC and CE for the characterization of supramolecular objects of LON was assessed