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Displaying theses 1-10 of 635 total
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H. Lin
Master programme: Chemistry - Molecular design, synthesis and catalysis June 4th, 2018
Institute: VU / Chem. & Pharm.Sc. Research group: VU Synthetic and Bio-Organic Chemistry Literature thesis Supervisor: Romano Orru
Catalysis in Esterification Reactions
Carboxylic esters are one of the most common functional groups in organic molecules. Thus, several types of esterification methods have been invented to obtain carboxylic esters. One of the traditional esterification methods is the Fischer reaction, which is based on acid-mediated condensation of carboxylic acids with alcohols. Other well-known esterification methods include Steglich and Mitsunobu reactions, which also have been widely used in academia. Despite these well-established esterification reactions, milder and more sustainable methods to obtain esters are still desired. To this end, a wide variety of catalytic systems has been constructed in order to efficiently afford esterified products without the employment of excess reagents and harsh conditions. Current catalysis in esterification includes the utilization of main group elements as well as transition metals. The Lewis acidity and electronic properties of catalytic centers also lead to various esterification mechanisms. In this report, different types of catalytic systems in esterification will be discussed. Furthermore, the possible application of esterification for producing biodegradable materials such as polyesters will be presented. The goals of this study are to present the advances of current esterification methods, and to illustrate catalysis in esterification is still an interesting and ongoing research area.
picture that illustrates the research done
Scientific abstract (pdf 1K)   For more info or full text, mail to: r.v.a.orru@vu.nl

H. Lin
Master programme: Chemistry - Molecular design, synthesis and catalysis June 4th, 2018
Institute: VU / Chem. & Pharm.Sc. Research group: VU Synthetic and Bio-Organic Chemistry Graduation thesis Supervisor: Eelco Ruijter
The Synthesis of the Derivatives of Pyrimido[4,5-d]pyrimidines through Nickel Catalyzed Isocyanide Insertion Reactions
Pyrimidopyrimidines are fused heterocyclic compounds which are known for their bioactivities and pharmaceutical applications. Consequently, there is significant interest in efficient methods to synthesize of these compounds. However, current synthetic methods suffer from indirect synthetic routes and limited scope of targeted molecules. In this research project, an efficient way of synthesizing pyrimido[4,5-d]pyrimidine derivatives by nickel-catalyzed isocyanide insertion reactions is reported. To this end, a number of diversely substituted amidines and a wide variety of isocyanides have been utilized to extend the scope of the reactions. The research results illustrate this methodology is efficient for insertion reactions to synthesize diversely substituted pyrimido[4,5-d]pyrimidines.
picture that illustrates the research done
Scientific abstract (pdf 1K)   For more info or full text, mail to: e.ruijter@vu.nl

M. Vurgun
Master programme: Chemistry - Analytical Sciences May 2nd, 2018
Institute: VU / Chem. & Pharm.Sc. Research group: VU Environment and Health Graduation thesis Supervisor: Pim E. G. Leonards
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Developing a Method for the Analysis of Phosphorylated Flame Retardants and their Diester Metabolites in Human Breast Milk
Phosphorylated flame retardants (PFRs) are used as a replacement for other flame retardants, since these compounds were supposed to be less toxic to the environment and health. However, studies show that some PFRs could be harmful for humans. Some PFRs can be metabolized forming – among other metabolites – diester metabolites (METAs). Limited studies showed the presence of PFRs in human breast milk. The aim of the study was to develop a method for the analysis of these PFRs and METAs in human breast milk. High-performance liquid chromatography tandem mass spectrometry using a triple quadrupole was chosen to separate and measure the PFRs and METAs. To enable an additional sample clean-up, on-line solid phase extraction (SPE) was successfully added to the system. For the sample preparation of the human breast milk samples, SPE was tested but showed limited throughput and a lack of robustness. As an alternative so-called “quick, easy, cheap, effective, rugged, and safe” QuEChERS method often used for pesticides and insecticides analysis was used and optimized for the PFRs, METAs, and the removal of the matrix. The sample preparation should be further developed. Once the method is fully developed, it can be validated so that its performance can be assessed.
picture that illustrates the research done
Scientific abstract (pdf 2K)   For more info or full text, mail to: pim.leonards@vu.nl

J. Kesselaar
Bachelor programme: Scheikunde April 12th, 2018
Institute: HIMS Research group: Analytical Chemistry Graduation thesis Supervisor: Noor Abdulhussain
Fused Silica Capillaries Coated with Titanium Dioxide and Tested with Capillary Electrophoresis
I have done my bachelor thesis with the analytical group at HIMS on the University of Amsterdam with the Separation of A Million Peaks (STAMP) project. The goal of this project is to create a chip that is possible to preform a 3 dimensional spatial separation, where the first two dimensions have to be spatial separations in order for it to work. One example of a spatial separation is isoelectric focusing (IEF), therefore a 2 dimensional titanium separation chip has been designed and 3D-printed. In this chip the first dimension is a capillary for the IEF, but IEF has not been performed yet on titanium dioxide, therefore in my thesis I had to coat silica based capillaries with titanium dioxide and tested these with CE and IEF. The conclusion of the testing with the capillary electrophoresis on titanium was that there was a difference in the electrosmotic flow, which is the flow that is needed to perform the separation, when titanium dioxide was used compared to a fused silica capillary. Eventually isoelectric focusing was researched and the result did not show any promise, therefore it was recommended to coat the 2 dimensional titanium chip in order to use it properly for IEF.
picture that illustrates the research done
Scientific abstract (pdf 3K)   For more info or full text, mail to: n.abdulhussain@uva.nl

L.V.A. van Duin
Master programme: Chemistry - Analytical Sciences March 9th, 2018
Institute: UvA / Other Research group: UvA / Other Graduation thesis Supervisor: Karlijn Bezemer
Chemical Profiling of Erythritol TetraNitrate (ETN) for Forensic Explosives Intelligence
Information beyond identification of ETN could be used to assist in criminal investigations. UPLC-APCI-HRMS methods were developed for the quantification of ETriN, and screening of additional impurities in intact ETN. This study characterized the concentrations of ETriN in recrystallized ETN (0.002 – 0.11 wt% 1,2,3-ETriN, and 0.040 – 0.54 wt% 1,2,4-ETriN) and crude ETN (0.34 – 1.747 wt% 1,2,3-ETriN, 0.81 – 2.17 wt% 1,2,4-ETriN). Additionally the effects of different synthesis routes (mixed acid and nitrate salt methods), including multiple synthesis conditions, and usage of different erythritol precursors have been investigated. To conclude, no differences were found in the chemical profile when various erythritol precursors were used during synthesis. Also, no differences in ETriN concentrations were detected when ETN was synthesized using two different synthesis method. However, it was possible to discriminate between crude and recrystallized ETN batches based on crystal features, ETriN concentrations and the detection of EDiN and EMN. Furthermore, differentiation was achieved between crude and neutralized crude ETN batches based on the amounts of EMN found. A large quantity of EMN was removed by neutralizing ETN with a basic solution. In addition, markers were suggested which could be used to differentiate between intact and post-explosive samples.
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Scientific abstract (pdf 1K)   For more info or full text, mail to: k.d.b.bezemer@uva.nl

W.C. Knol
Master programme: Chemistry - Analytical Sciences March 5th, 2018
Institute: HIMS Research group: Analytical Chemistry Literature thesis Supervisor: Wim Kok
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Studying protein-protein and protein-polysaccharide interactions
This thesis discusses several methods for studying protein-protein and protein-polysaccharide interactions, with an emphasis on capillary electrophoresis methods.
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Scientific abstract (pdf 3K)   Full text (pdf 2037K)

F.C.M. Kuijpers
Master programme: Chemistry - Analytical Sciences March 1st, 2018
Institute: VU / Chem. & Pharm.Sc. Research group: VU Analytical Chemistry and Applied Spectroscopy Literature thesis Supervisor: G.W. Somsen
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Capillary electrophoresis; one technique to completely characterize biopharmaceuticals
Biopharmaceuticals – therapeutically active biomolecules – have become an important class of drugs. They have proven to be efficient in the treatment against many diseases, such as cancer, diabetes, autoimmune disorders, and anemia. As a result of expression, purification, and storage processes, biopharmaceuticals can undergo post-translational modifications, degradation, and aggregation, which can highly affect the efficacy and stability of the product. Therefore, the product must be subjected to characterization analyses in order to monitor the physical, chemical, biological, or microbiological properties of the product. This review describes the ability of capillary electrophoresis (CE) to completely characterize a biopharmaceutical in terms of their structural and physicochemical properties. We describe the following characterization analysis categories ordered from intact to amino acid level: size variants, charge variants, aggregates, N-linked glycosylation, O-linked glycosylation, and amino acid sequence. For the analysis of charge and size-based variants, CE is extensively developed allowing even more successful separations compared to chromatographic techniques. The same applies for analyzing N-glycans and O-glycans. Determination of aggregates and amino acid sequencing is mainly performed using other techniques than CE, although CE could also be applied for these analyses. Thus, CE can be considered as a suitable technique to completely characterize biopharmaceuticals.
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Scientific abstract (pdf 55K)   Full text (pdf 6238K)

T. Keijer
Master programme: Chemistry - Molecular design, synthesis and catalysis February 28th, 2018
Institute: HIMS Research group: Homogeneous Catalysis Graduation thesis Supervisor: J.N.H Reek
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Light Harvesting Artificial Reaction Centers: Exploring The Synthesis Of Reaction Center Mimics For Photocatalytic Proton Reduction
Storing solar power in a chemical fuel is a desired innovation towards sustainable energy. Hydrogen gas is a promising fuel and may use water as a feedstock. To produce hydrogen gas from water using light, we drew inspiration from natural systems. Natures’ complex biomolecules utilise fundamental principles to achieve water-splitting. By simplifying these principles, one can produce the core part of an artificial enzyme. This resulted in the design of a new artificial reaction center, based on so-called supramolecular spheres. These spheres self-assemble when the right chemical components are combined in solution. By attaching external and internal functionalities to the sphere building-blocks they attain properties resembling natural enzymes. The chemistry to built such molecular assemblies was explored during this research project. As a result, the best route to produce these structures was discovered.
picture that illustrates the research done
Scientific abstract (pdf 2K)   For more info or full text, mail to: J.N.H.Reek@uva.nl

O.J.M. Hofman
Bachelor programme: Scheikunde February 2nd, 2018
Institute: HIMS Research group: Biomolecular Systems Analytics Graduation thesis Supervisor: Prof. Garry Corthals
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Analysis of sodium diclofenac and carbamazepine by surface acoustic wave nebulization – mass spectrometry
Mass spectrometry (MS) is a popular technique to identify and quantify different molecules in a sample based on their mass-to-charge (m/z) ratio. Since every molecule has own specific mass depended on the atoms whereof it consists, every single molecule also has its own unique m/z ratio which is effectively used to distinguish between molecules in MS. The consecutive steps in MS include; ionization of the molecule (giving the molecule a positive or negative charge), followed op by separation of the m/z ratios of the different molecules in sample, and finally detection of the different molecules. A spectrum is produced by the mass spectrometer of all different m/z values and corresponding signal intensities. From this spectrum, one can determine the amount and what molecules are present in the analyzed sample. This thesis compares electrospray ionization (ESI) with surface acoustic wave nebulization (SAWN) for the analysis of sodium diclofenac and carbamazepine in water samples by MS. SAWN is new technique which has the potential to reduce analysis time and costs for MS reserach.
picture that illustrates the research done
Scientific abstract (pdf 2K)   For more info or full text, mail to: g.l.corthals@uva.nl

M. Trisna
Master programme: Chemistry - Analytical Sciences January 30th, 2018
Institute: SILS Research group: Mass spectrometry of biomacromolecules Graduation thesis Supervisor: Dr. Eva de Rijke
Method development of an isotopic traceability tool for determination of the geographical origin of roses by Isotope Ratio Mass Spectrometry (IRMS)
The growing number of government rules regarding agricultural products such as flowers and plants lead to growers having to meet strict regulations regarding safety, environment, sustainability and traceability. Therefore, this study aims to develop isotope analysis technology for provenance determination of roses. The focus will be on development of methods using an instrument called isotope ratio mass spectrometry (IRMS) for geographical origin traceability. The approach consisted of the analysis of hydrogen, oxygen, carbon and nitrogen isotopes of the rose samples. IRMS is known as one of the most advanced techniques for isotope analysis nowadays. In this work, it was used for the determination the geographical origin of roses by measuring the relative abundance of element isotopes in the sample. The isotope ratio of these elements reflects the unique and representative fingerprints of the particular environment, which is related to the biological, chemical and physical processes in the plants. Therefore, it offers the possibility to discriminate roses of different origins. The results provide proof that the IRMS method based on hydrogen, oxygen, carbon and nitrogen isotopes, offers a potential technique for the geographical origin determination of roses from Ecuador, Kenya and the Netherlands.
picture that illustrates the research done
Scientific abstract (pdf 2K)   For more info or full text, mail to: e.derijke@uva.nl

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