Silver coordination polymers for measuring arsenic levels in water

Inventors

Campbell, Michael G. • BOSTICK, Benjamin C. • REICH, Natasha

Assignees

Barnard College • Columbia University

Abstract

Measurement devices can be used for identifying concentration of arsenic species in water samples. The measurement devices can take the form of test strips including a substrate with at least one testing region that includes an amount of a testing medium. The silver reagent includes a polymer framework and a silver component that is stabilized by the framework, yet remains reactive enough to function as a colorimetric sensor for arsenic, e.g., ((Ag(H2btc))(Ag2(Hbtc)))n. The initially substantially colorless testing medium exhibits a color change response when exposed to arsenic species, e.g., arsine, generated from samples including as little as 5 ppb arsenic, with an increasingly dark color as the concentration of arsenic is increased. Test strips fabricated with the silver coordination polymer display robust stability towards both light and water, allowing for an alternative to mercury-based field test kits in real-world field tests under direct sunlight and high humidity conditions.

Core Innovation

The invention relates to detecting a concentration of arsenic in a medium by obtaining a sample, administering the sample to a substrate that includes an amount of a silver reagent, and measuring a characteristic change of the silver reagent. The silver reagent includes a polymeric framework including elemental silver, at least one silver salt, at least one silver compound, or combinations thereof, and the testing region includes an amount of the silver reagent to identify a concentration of arsenic species in a medium.

In the described polymeric framework, the silver reagent includes a polymeric framework stabilized with silver(I), and in particular includes a silver reagent comprising the species Ag(H2btc) and Ag2(Hbtc) in the form (Ag(H2btc))(Ag2(Hbtc))n. The arsenic response is a characteristic change of the silver reagent, including a colorimetric change that darkens upon arsenic exposure, and the polymeric framework is water-insoluble for the silver reagent used in the substrate testing region.

The invention also includes making the measurement device by providing a substrate and administering an amount of the silver reagent to at least a portion of the substrate to form a testing region positioned thereon, where the silver reagent includes a polymeric framework including elemental silver, at least one silver salt, at least one silver compound, or combinations thereof. The measurement can be performed for arsenic species in surface water, groundwater, and industrial effluent.

Claims Coverage

The independent claims cover three aspects: a method of detecting arsenic concentration in a medium, a measurement device with a testing region containing a silver reagent, and a method of making such a measurement device. Across these independents, the core inventive focus is the use of a polymeric-framework silver reagent integrated into a substrate testing region for arsenic species identification via a measurable characteristic change.

Overall, the independent claims consistently require a substrate-based testing region using a silver reagent that includes a polymeric framework with elemental silver and/or silver salts/compounds, and they define arsenic identification through measuring a characteristic change in the silver reagent. The claim set also extends these concepts to a measurement device and to a method of making the device by administering the silver reagent onto a substrate to form the testing region.

Stated Advantages

Documented Applications