Title

The Effect of Mg and Ca in Seawater on the MRI Contrast Agent Gd-DTPA

Abstract

The concentration of gadopentetic acid (Gd-DTPA), an MRI contrasting agent, has increased in urban waterways over the past three decades. While Gd-DTPA is so stable in freshwater that toxic Gd3+ is unlikely to be released, little is known about the stability of this complex in marine environments. At high salinity, Mg and Ca may reduce the concentration of free DTPA and release Gd3+ into the environment. In my study, the stability constants for complexes of DTPA with Ca and Mg were measured at seawater ionic strength by potentiometric titration to better understand the behavior of Gd-DTPA in marine environments. A side-reaction coefficient for DTPA in seawater was calculated from these constants to predict the speciation and complexation of DTPA in marine environments. I conclude that Gd-DTPA largely dissociates in seawater, releasing toxic Gd3+ to marine ecosystems.

Faculty Sponsor

Frank Dunnivant

Tracks

Secrets of the Deep II

Terms of Use

ARMINDA Terms of Use

Location

Science 100

Presentation Type

Oral Presentation

Research Funding Source or OCS Program

National Science Foundation

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Apr 11th, 2:30 PM Apr 11th, 2:45 PM

The Effect of Mg and Ca in Seawater on the MRI Contrast Agent Gd-DTPA

Science 100

The concentration of gadopentetic acid (Gd-DTPA), an MRI contrasting agent, has increased in urban waterways over the past three decades. While Gd-DTPA is so stable in freshwater that toxic Gd3+ is unlikely to be released, little is known about the stability of this complex in marine environments. At high salinity, Mg and Ca may reduce the concentration of free DTPA and release Gd3+ into the environment. In my study, the stability constants for complexes of DTPA with Ca and Mg were measured at seawater ionic strength by potentiometric titration to better understand the behavior of Gd-DTPA in marine environments. A side-reaction coefficient for DTPA in seawater was calculated from these constants to predict the speciation and complexation of DTPA in marine environments. I conclude that Gd-DTPA largely dissociates in seawater, releasing toxic Gd3+ to marine ecosystems.

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