Determination and Characterization of Arsenic and Selenium Species in Plants by HPLC-ICPMS/ESIMS

Date

2024-1-26

Author

Özkan, Canan

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It has been broadly recognized that selenium (Se) is beneficial element with many functions but arsenic (As) is known toxic depending on their concentrations and species in plant cells. The interactions of As and Se with the plant detoxification agents like glutathione (GSH) in vitro medium are very important to understand the mechanism of As and Se in plant. This study aims to investigate the antagonistic or synergistic effects of inorganic As and Se species on the binding mechanism of inorganic Se and As species with GSH in a synthetic medium at pH 3.0, 5.0, and 7.0 to mimic plant cell conditions. Firstly, the binary and ternary systems were studied in terms of stoichiometry and pH via UV-Vis absorption spectroscopy and LC-UV. For the binary systems, As(III) did not affect the stability of the Se(SG)2 complex, but the addition of Se(IV) to As(SG)3 antagonistically affected the stability of As(SG)3 complex. For ternary systems at various molar ratios, the Se(IV)+GSH reaction was processed. Secondly, the binary and ternary systems were studied from the aspect of qualitative via LC-DAD/MS and LC-MS/MS. The As(III) had no effect to the stability of Se(SG)2 and the antagonistic effect of Se(IV) on the stability of As(SG)3 in the binary systems. Also, GSH was prefer Se(IV) to form complex in all ternary systems. A by-product Glutathione trisulfide (GSSSG) formation was also detected and its’ structure is confirmed using LC-MS/MS in systems. The formation mechanism of GSSSG in formic acid medium was proposed for systems. Lastly, the ternary systems at pH 3.0 and 5.0 were studied via LC-ICP-MS and ICP-MS to determine species and their concentrations. Using the concentrations of species in ternary systems, the conditional formation constants were calculated as 2.6 ×107 and 1.9×1015 at pH 3.0 and as 1.4×107 and 4.4×1017 at pH 5.0 for As(SG)3 and Se(SG)2, respectively. In conclusion, Se(IV) has an affinity for binding GSH molecule compared to As(III) in plant cell mimic conditions.

Subject Keywords

Arsenic, Selenium, Glutathione, UV-Vis spectroscopy, LC-DAD/MS, LC-ICP-MS

URI

https://hdl.handle.net/11511/108744

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Graduate School of Natural and Applied Sciences, Thesis