Date of Award

Spring 1-1-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

Karl G. Linden

Second Advisor

James Rosenblum

Third Advisor

Zhiyong J. Ren

Abstract

Environmental water mixtures have become challengingly complex to analyze for toxicological compounds and emerging contaminants. To enhance water characterization, this study focused on developing a framework based on effects-directed analysis (EDA) coupled with chemical separation and qualitative analysis. Six estrogenic compounds, Ethylparaben (EPB), Bisphenol A, 17β-estradiol (E2), 2,4,6-trichlorobiphenyl (TCBP), Octylphenol (OP) and Bis-(2-ethylhexyl)-phthalate (DEHP), were chosen to create a synthetic water mixture that was used to develop and test a separation framework consisting of two-steps: liquid-liquid extraction (LLE) followed by solid phase extraction (SPE). Based on the polarity of these compounds and their adsorption onto the SPE phases, the procedure generated six fractions from the simulated mixture: a concentrate and a flow-thru fraction for each of the polar, mid-polar and non-polar phases. The fractions were then assessed for cytotoxicity and estrogenic activity using yeast estrogen screening (YES), an in-vitro bioassay conducted with a recombinant yeast strain, Saccharomyces cerevisiae. All the fractions were concurrently analyzed by Liquid Chromatography Mass Spectrometry (Ion Trap) and Gas Chromatography Flame Ionization Detection for the identification and quantification of the target compounds. The compounds were distributed among four of the six fractions namely polar concentrate, mid-polar concentrate and flow-thru, along with the nonpolar concentrate. This was validated by YES results of the synthetic water mixture and select fractions exhibiting a relative estrogenic activity (% REA) ranging between 80%-95% while the fractions devoid of estrogenic compounds showed non-detectable levels of REA. The developed framework coupled with an EDA approach could be cost-effective and time saving, while providing insights into chemical nature of contaminants and subsequent identification, that could be used to inform their removal through targeted treatments. Overall, this generalized method could be applied to environmental water samples as an approach to improve toxic identification and evaluation.

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