Project Report

Pharmaceuticals in Our Water: A New Zealand Perspective Every time someone takes a prescription or over-the-counter medicine, only a portion of the drug is metabolized by their body. The remainder is excreted in active pharmaceutical form and makes its way through a sewage treatment plant to natural bodies of water, and eventually perhaps to our drinking water supply. For the past four years, I have studied the behavior of various pharmaceutical compounds in water. I began by focusing on the fluoroquinolones, a set of antibiotics commonly taken by both humans and animals. I studied their degradation under gamma irradiation, measured their rate constants with hydroxyl radicals and hydrated electrons, and identified several byproducts that are formed when they break down in solution. Then, I shifted to a set of three antidepressants, which are also widely utilized by patients. For this study, I focused on photochemical fate, attempting to understand the behavior of the compounds under natural sunlight rather than engineered treatment. Once again, I obtained degradation rates and identified reaction byproducts. This past summer, I had the opportunity to perform research at the University of Otago in Dunedin, New Zealand, through the NSF’s East Asia and Pacific Summer Institute. While I have traveled abroad before, this was the first time I was studying in a foreign country, and I felt apprehensive yet excited. Upon my arrival in the country, the Royal Society of New Zealand gave all the EAPSI participants a 3-day orientation, which included an introduction to the local culture, information on the research environment, and general tips on the New Zealand lifestyle. After this, I arrived in Dunedin and settled down in my apartment, ready and anxious to begin. My research at the University of Otago focused on enoxacin, a fluoroquinolone antibiotic. I utilized an ultraviolet light reactor to degrade the compound, and monitored the concentration as a function of time by high performance liquid chromatography. This enabled me to describe the degradation kinetics. I then repeated this process under several sets of conditions, in order to analyze the impact of various factors on the degradation rate. I discovered that hydrogen peroxide increases the rate of degradation, as does a combination of hydrogen peroxide and ferrous ions. This last condition, commonly known as the photo-Fenton reaction, is a common technique used to produce reactive oxidants that can be used to break down pharmaceuticals and other compounds. I also obtained a sample of sewage from the Dunedin wastewater treatment plant, in order to study the behavior of enoxacin in real-world conditions. In addition, I ran experiments to monitor the total organic carbon in the enoxacin sample during irradiation. Finally, I identified the byproducts formed during the irradiation process through mass spectroscopy and nuclear magnetic resonance spectroscopy. My research, however, was only a portion of my experience in New Zealand. I also had the opportunity to immerse myself in a foreign culture, meet the local people, and experience a lifestyle surprisingly different from my own. Besides giving me the opportunity to perform scientific research in a foreign university, EAPSI provided me with a chance to develop new collaborations with scientists from all over the world, and I hope to remain in contact with many of them as I progress through my career. This program has certainly been one of the highlights of my graduate education.

National Science Foundation (NSF)
Office of International and Integrative Activities (IIA)
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Carter Kimsey
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Santoke Hanoz B
Huntington Beach
United States
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