Student Meeting 2017

Kathryn Renyer

Do Microplastics Enhance the Uptake of Toxins in Earthworms?





Alan Wong

UHPLC-MS/MS Quantitative Analysis of Estrogen Metabolites in Human Serum

Women suffering from menopausal symptoms often turn to hormone therapy, but this has been known to increase risk of breast cancer. Botanical dietary supplements, which are reported to alleviate these symptoms, are increasingly popular as an alternative; however, many of these plants has not been well studied for safety and efficacy. Estradiol and estrone are hydroxylated by cytochrome P450 enzymes at the 2- or 4-positions of the A-ring, corresponding to nontoxic and genotoxic pathways, respectively. These catechol products are substrates for catechol-O-methyl transferase, which detoxifies the 4-hydroxy estrogen metabolites. Consumption of botanical dietary supplements or hormone therapy might alter the formation of these oxygenated metabolites and thereby decrease or increase risk of estrogen related disease such as breast cancer. Therefore, these oxygenated estrogen metabolites can be used as biomarkers of breast cancer risk. Reliable quantification of estrogenic metabolites has been a challenging bioanalytical problem as these compounds are difficult to separate due to their similar chemical properties, and are in the low pg/mL range in serum and plasma of women.

This seminar will discuss a two-step derivatization method using N-methyl pyridinium-3-sulfonyl (NMPS), and quantitation by ultra-high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) using selected reaction monitoring (SRM). This derivatization method involves the addition of a preformed quaternary amine; therefore, protonation of the estrogen metabolite derivative is not required for positive ion electrospray. When compared to previous approaches in the literature, the NMPS method provides increase in sensitivity and significantly suppresses matrix effects. This assay will be used to analyze clinical serum samples obtained from postmenopausal women taking botanical supplements such as black cohosh, red clover, hops and Prempro. We hope to use these samples to determine biomarkers to assess the risk of breast cancer.


 Determination of Illicit Designer Drugs and Their Metabolites in Wastewater

Xiolmara Martinez

Many new drugs of abuse have been synthesized recently. These “designer drugs” are intended to have similar properties to known illegal hallucinogenic or narcotic substances, but are technically unregulated due to their slightly altered molecular structures. Our work in identifying some of these drugs and drug metabolites in wastewater by GC-MS will be presented in this talk.