Document Type

Honors Thesis

Publication Date

5-2014

Abstract

The goal of our work is to provide marine scientists with a detection system which can be mounted on buoys and gliders for measuring the amount of iron (III) in sea water. Iron is the limiting nutrient for phytoplankton growth. Since phytoplankton play a key role in global carbon cycles and global warming, the iron in seawater does as well. This thesis is meant to be a proof-of-concept for a new approach to measuring iron in seawater. The essential elements of the research discussed herein include identifying particulate beads which are optically transparent in the visible region, modifying the surfaces of these beads to reversibly bind iron (III) from water, and measuring the detection limit directly on the transparent beads using UV-Visible (UV-Vis) spectroscopy. Agarose beads were selected and shown to be semi-transparent in water. These beads were treated with polystyrene50-b-poly(acrylic acid)180; the acrylic acid portion of the polymer was then reacted with iron (III) chelator desferrioxamine B using EDC as a catalyst. Infrared spectroscopy was used to show that the block copolymer and DFB had attached to the beads. UV-Vis spectroscopy was used to study the iron uptake by these beads, using the red color produced when DFB chelates iron (III). The amount of time needed for the beads to take up iron (III) from a solution and the saturation point of the beads was also determined. It was shown that detection of low parts per trillion is possible and that at pH 7.5, the presence of oxalate would not affect iron (III) uptake.

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