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Padilla Mercado Masters Thesis.pdf (2.12 MB)

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Development of a teaching coulometry instrument for the direct determination of sulfur compounds and of zinc indirectly

Padilla Mercado, Jeralyne Beatriz
http://orcid.org/0000-0002-8980-0594
http://rave.ohiolink.edu/etdc/view?acc_num=miami1499251632209504

Abstract Details

2017, Master of Science, Miami University, Chemistry and Biochemistry.
The development and characterization of a teaching coulometry instrument for on-line data acquisition is described. A constant current source connected to nonisolated Pt electrodes in a 150-mL beaker served as the cell where the iodine titrant is electrochemically generated and allowed to react with the analyte reducing agent. A photodiode monitored the darkening of the solution due to the starch-iodine complex permitting this titration curve to be stored by a multifunctional chemical analysis system used for teaching for subsequent graphical analysis. Characterization of the instrument for direct analyte determination is performed with ascorbic acid, thiols, thiosulfate, and bisulfite. The number of electrons per mole of thiol for iodine titration of glutathione and N-acetylcysteine varied as a function of pH, indicating different reaction pathways. Ascorbic acid and the thiols are determined in dietary supplements with a recovery of 90-100%. The indirect determination of zinc after its complexation with cysteine was performed in alkaline media. The titration endpoint times of cysteine with zinc are proportionally longer as compared to cysteine itself. The determination of ascorbic acid and zinc in a supplement could be titrated sequentially without changing the sample. Recovery of zinc ranged from 96-112% with a RSD range of 6-11%.
Neil D. Danielson (Advisor)
Jiangjiang Zhu (Committee Chair)
Dominik Konkolewicz (Committee Member)
Richard Bretz (Committee Member)
96 p.
Analytical Chemistry; Science Education
constant current coulometry; on-line detection; sulfur compounds; zinc; cysteine chelation

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Citations

  • Padilla Mercado, J. B. (2017). Development of a teaching coulometry instrument for the direct determination of sulfur compounds and of zinc indirectly [Master's thesis, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1499251632209504

    APA Style (7th edition)

  • Padilla Mercado, Jeralyne. Development of a teaching coulometry instrument for the direct determination of sulfur compounds and of zinc indirectly. 2017. Miami University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1499251632209504.

    MLA Style (8th edition)

  • Padilla Mercado, Jeralyne. "Development of a teaching coulometry instrument for the direct determination of sulfur compounds and of zinc indirectly." Master's thesis, Miami University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1499251632209504

    Chicago Manual of Style (17th edition)

miami1499251632209504
2,849
© 2017, some rights reserved.Creative Commons License Development of a teaching coulometry instrument for the direct determination of sulfur compounds and of zinc indirectly by Jeralyne Beatriz Padilla Mercado is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Miami University and OhioLINK.