Chemistry - Student Works

Permanent link for this collection


Recent Submissions

Now showing 1 - 5 of 7
  • Item
    Silicone wristbands as personal passive samplers: assessing exposure to organophosphate flame retardants
    (2020) Molenaar, Danielle; Ross, Matthew
    Organophosphate flame retardants (OPFRs) are used as additives in a variety of industrial and commercial products, such as furniture and electronics, to meet fire resistance standards. However, OPFRs have been associated with health effects, including neurotoxicity, hormonal changes, and cancer; therefore, insight into levels of exposure is necessary for health and risk assessments. An individual’s exposure to OPFRs can be measured using silicone wristbands as passive samplers, which make use of the tendency for a chemical to equilibrate between the solid phase (the sampler) and air to measure personal exposure to contaminants over time. Because OPFRs are frequently used in electronics, this study aimed to examine correlations between electronic use and personal exposure to OPFRs. Silicone wristbands were cleaned to remove surface contaminants, and then deployed to participants to wear for one week. Following deployment, the adhered compounds were extracted and analyzed using gas chromatography-mass spectrometry. While deployed, participants filled out a questionnaire indicating their weekly electronic use, which was used to draw correlations between electronics and exposure to OPFRs. The median concentration of OPFRs on wristbands were found to be about 6300ng/wristband, with high variability between individual wristbands. This project will be one of the first in Canada to use silicone wristbands as personal samplers to address exposure to OPFRs in relation to electronic use, and thus will prove useful in risk assessment due to the increasing use of electronics in society.
  • Item
    Sulfur composition of MacEwan meteorites
    (2018) Coyle, Amanda; Hilts, Robert
    Meteorites contain a wide variety of sulfur species: sulfates, sulfides, organic sulfur, and elemental sulfur. Sulfur in meteorites is thought to be in a form that resembles the sulfur on Earth before the formation of the hydrosphere. Thus, through investigations of the composition of these meteorites, insight can be gained regarding the formation of the Earth, and consequently, the formation of life. The goal of this project was to perfect wet chemistry techniques to deferentially extract the sulfur species to determine the relative masses of the different species. Multiple extractions with different solvents were used to separate the species based on their chemical and physical properties. Although all the species contain sulfur, the properties of them vary immensely. The MacEwan meteorites collection contains a wide variety of meteorites, including carbonaceous chondrites and a lunar sample. The techniques developed during the beginning phase of the project were applied to extract from one of the rocks, and will be used in future projects to extract sulfur from all rocks in the collection.
  • Item
    Primordial sulfur and the origin of life
    (2018) Coyle, Amanda; Hilts, Robert
    The study of meteorites can give insight regarding the chemical composition that was present when the solar system was being created. The elements in meteorites have not undergone extensive changes since they were formed billions of years ago, so they are thought to resemble those on Earth before the formation of the hydrosphere. This can lead to information regarding the formation of the solar system, Earth, and consequently, life. Sulfur is of interest because it has essential roles in biochemistry and a prevailing theory regarding the origin of life is that it began in an iron-sulfur world. By determining the sulfur composition of meteorites and the isotopic ratios – ratio of atoms of the same element with different atomic masses – we hope to determine the processes behind for formation of the form of sulfur responsible for the creation of life. This first stage of the project was to perfect wet chemistry and analytical techniques to extract and quantify sulfur species from meteorites. The development of the techniques required reading research literature, testing, and altering the techniques while working with a meteorite simulant. Multiple extractions with different solvents were used to differentially separate the sulfur species based on their chemical and physical properties. The extractions were pure with high yields. These techniques will be used to extract sulfur from the meteorites in the MacEwan collection, which will then undergo isotopic analysis.
  • Item
    Molecular modelling and kinase assay for CePNKP binding to DNA
    (2017) Manary, Brandon; Bernstein, Nina; Llano, Jorge
    Computational techniques of homology modelling, enzyme–substrate docking, and molecular dynamics were applied to elucidate the structure and substrate binding properties of the DNA repair enzyme polynucleotide kinase/phosphatase from the nematode C. elegans (CePNKP). PNKP is involved in the repair of DNA strand breaks, a form of DNA damage caused by reactive oxygen species, ionizing radiation and certain chemical mutagens. Mutations in human PNKP have been associated with the neurological disorders Microcephaly with Intractable Seizures (MCSZ) and Ataxia Oculomotor Apraxia 4 (AOA4). In addition, human PNKP has been identified as a potential drug target for the development of chemo- and radiosensitizing agents for cancer treatment. CePNKP is a useful model system for studying the human enzyme. The substrate preference for both human and C. elegans PNKP has been investigated, and found to be similar, with higher selectivity for recessed over blunt DNA ends. However, CePNKP exhibits a more exclusive preference for recessed DNA ends than human PNKP. To elucidate the reason for the unique substrate specificity of CePNKP, the structure of CePNKP in complex with its DNA substrate must be determined in atomistic detail by molecular modelling. The generated structural model is compared with our experimental results of kinase activity assays of wild-type CePNKP.
  • Item
    Quantification of Escherichia coli via analysis of β-glucuronidase enzyme concentrations
    (2017) Andersen, Brody; Mugo, Samuel
    Concentration of Escherichia coli can be quantified based on a digestive enzyme produced by 97% of E. coli strains called β-glucuronidase (β-GUS). When in contact with a β-glucuronide (β-GLU) molecule, the enzyme cleaves the β-GLU segment off the molecule, leaving the remaining fragment untouched. The remaining fragment can serve as a marker for the presence of the enzyme and can be quantifiably calibrated to determine the concentration of the E. coli in each sample. For a colourimetric method approach, 4-nitrophenol-β-D-glucuronide (4-NβDg) can be used as a dye for the enzyme. The remainder of the molecule after enzymatic cleavage is a 4-nitrophenol, which is blue in colour. The change in colour can be quantified based on a calibration curve. For an electrochemical method approach, 4-NβDg can also be used because 4-nitrophenol gives a characteristic cyclic voltammogram on a potentiostat. The change in resistance of 4-nitrophenol can be determined and calibrated to show the concentration of the E. coli in each sample. This research is ongoing and does not have the finalized results on the outcome of the work described above. Additional information can be provided as necessary.