Development of Molecularly Imprinted Polymers for Chlorpyrifos, 18-9168

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Principal Investigators
Henry W. Oviatt
Mark Van Dyke
Michael A. Miller

Inclusive Dates: 10/01/99 - Current

Background - Chlorpyrifos, chemical name phosphorothioic acid, O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) ester, is the insecticide commonly known as Dursban, Lorsban, or Pyrinex. Other trade names are Brodan, Detmol UA, Dowco 179, Empire, Eradex, Paqeant, Piridane, Scout, and Stipend. Registered since 1965 and in use in more than 88 countries on more than 50 different crops, this pesticide has been the mainstay of crop damage prevention from parasitic organisms to date and is the most widely used organophosphate pesticide in the world. It has also commonly been used in and around homes for termite treatment and control of other destructive pests. Pressure from the public concerned with safety in and around their homes, however, has caused this pesticide to be phased out from residential use by the end of 2001.

The ubiquitous environmental presence of Chlorpyrifos around the world and the greater concern and environmental awareness of the public of pesticides in general have made environmental monitoring a commonplace activity. Rapid and specific tests for compounds of environmental significance such as Chlorpyrifos are opportunities to be explored and exploited.

Molecular imprinting is a generic term used for the synthesis of materials that possess an enhanced affinity for specific molecules. Typically, imprint sites are formed by performing a polymerization reaction in the presence of a "print" molecule and a solvent. As the polymerization reaction progresses, polymer forms around the print molecule. Removal of the print molecule leaves a void in the polymer with a greater affinity for the print molecule over other, similar small molecules. This method has been shown to be successful by many researchers, but typically involves numerous steps before a useful material results.

Approach - In this approach, the research team is aiming to eliminate many of the steps typically encountered in the molecular imprinting process. This project is directed toward the development of polymeric materials with characteristics for preferential binding of Chlorpyrifos. This method involves the synthesis of novel compounds with structural characteristics similar to the Chlorpyrifos molecule, and the subsequent use of these "templates" to form materials with high surface area and specificity toward the template molecule. Measurement of the activity toward Chlorpyrifos using competitive binding and standard analytical techniques should yield the degree of specificity of the imprinted polymers toward the target molecule. Success of this approach could lead to inexpensive, easily applied test kits for Chlorpyrifos. The technology and methodology developed in this program, however, should be generally applicable to other small molecules.

Accomplishments - Initiated in late 1999, this project had some early progress on the methods of material synthesis. In June 2001 with a change in the project manager, the project was re-evaluated and refocused on the original goals of the project with specificity to Chlorpyrifos. The team is currently making progress on the synthesis of analog compounds to be used as the imprinting templates.

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