Digitized Honors Theses (2002-2017)

Date of Award

12-2015

Document Type

Undergraduate Thesis

Degree Name

BS

Department

Biomedical Sciences

Faculty Mentor

Alexandra Stenson

Advisor(s)

Larry Yet, Ph.D., Jason Coym, Ph.D., Kevin White, Ph.D.

Abstract

Increased energy efficiency, reduced C02 emissions, lower prices, and simpler installation have expanded the use of cross-linked polyethylene (PEX) pipes as opposed to PVC and copper for potable water piping. PEX can be used on both an industrial scale and in households for hot and cold water transportation. Three different types of PEX pipes exist: PEX-A, PEX-B, and PEX-C; their differences lie in the methods used to manufacture them. Research regarding chemical compounds seeping from PEX piping, known as leachates, is scarce in the US and only slightly more abundant in Europe. The majority of this research has been limited to total organic carbon analysis, threshold odor number analysis, assimilable organic carbon analysis, and gas chromatography mass spectrometry (GCMS) for the determination of leachates from PEX piping into potable water. GCMS can identify compounds but is limited to nonpolar, volatile analytes. As Liquid Chromatography-Electrospray Ionization­ Mass Spectrometry (LC-ESI-MS) is selective for polar molecules, it can aid in expanding the list of detectable leachates. Three different brands of household PEX piping, consisting of one PEX­ A and two PEX-B pipes, were used for migration testing; the water samples were analyzed with Electrospray Ionization-Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry (ESI­-Ff -ICR-MS). Mass spectra of contact water show a multitude of peaks, differ from the mass spectra of the controls, and give insight into the structure of the compounds. Additionally, MS/MS data provide more information about the possible structures and molecular formulas of the compounds leaching into contact water. Masses detected are different from those previously identified in GCMS. Therefore LC-ESI-MS appears a viable method for expanding the range of detectable leachates.

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