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Final Progress Reports: University of California-Berkeley: Nanotechnology-Based Environmental Sensing

Superfund Research Program

Nanotechnology-Based Environmental Sensing

Project Leader: Catherine P. Koshland
Co-Investigator: Peidong Yang
Grant Number: P42ES004705
Funding Period: 2006 - 2017
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Final Progress Reports

Year:   2010 

Investigators from the Superfund Research Program at Berkeley have built collaborations between several departments and Lawrence Berkeley National Laboratory to develop new methods for monitoring contaminants in the environment and in people.

Overall goals

Investigators are using new technologies to develop better ways to measure common contaminants that can be used in the field and that have lower costs and lower detection limits than methods available now. They are working on methods for arsenic, which is a pollutant of concern around the world, and mercury.

Spectroscopy methods to measure contaminants are based on interactions between a light beam of some kind and the chemical molecule to produce a pattern that can be examined to determine the composition of an unknown compound. The methods being developed are advanced forms that can detect very small quantities. The use of the very small nanomaterials increases this capacity to detect at low levels.

What has been done so far

Investigators have been working on detecting different forms of organic arsenic ("arsenate") compounds using a variety of silver nanoparticles. These are used in a spectroscopy method known as surface-enhanced Raman spectroscopy (SERS) sensing platforms. The specific form of organic arsenate being targeted is dimethylarsinic acid (DMA(V)). This is because this is the form of arsenic found in urine in animals. It is produced through metabolism of inorganic arsenic.

Investigators developed three types of silver nanoparticle sensors that allow the sensing platforms to be tailored for use in different applications. The sensitivity of the SERS platforms to detect DMA(V) was good from 1000 parts per million (ppm) to 1 ppm. This shows that the sensing platform possesses the potential of quantitatively determining the organic DMA(V) arsenic concentration at concentrations as low as 1 ppm.

Investigators use gold nanorods to detect mercury. When mercury combines with the nanorods, there is a measurable shift that can be detected using visible light. (This is due to the change in the surface plasmon frequency.) Investigators isolated single nanorods and observed how they change shape when exposed to mercury atoms.

Investigators are placing the nanorods on curved glass fibers to construct a sensor that can be used for both air and water sampling. When light is sent down the fiber, some of it interacts with the gold nanorods when the light strikes the boundary between the fiber and the air or water surrounding it. This allows them to sample in systems where the absorption of visible light is too large for conventional sampling.

What the investigators plan to do next

Investigators will continue their work on the methods for arsenic to differentiate and quantify inorganic and organic arsenic in a mixture. Attention will be paid to distinguishing the chemical finger print of DMA(V) and inorganic arsenate in these mixtures.

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