This Small Business Innovation Research Phase I project will demonstrate the feasibility of developing a novel lateral field excited (LFE) sensor for use as an organophosphate pesticide sensor. The technical objectives of the proposed project are: 1) to determine the selectivity to phosmet of the LFE sensor coated with polyepichlorohydrin and porous films; 2) to determine if the sensor is capable of detecting phosmet in the presence of blueberry juice alone and in the presence of an additional interferent; 3) to develop a simple sampling protocol for use at production or processing facilities. The use of porous silica materials for filtration and concentration will be investigated with the goal of improving sensor selectivity toward the target pesticide of phosmet. To achieve these objectives Phase I work will demonstrate that the LFE sensor is a vast improvement over both standard quartz crystal microbalances (QCMs) and QCMs with modified electrode geometries. If feasible, the Phase I work will result in a sensor platform that is highly stable and optimized for organophosphate pesticides detection. Additionally, a sampling protocol and a package design will be realized. The successful completion of the proposed project will result in a sensor for organophosphate pesticides that is sensitive, portable, inexpensive, and easy to use. Mainely Sensors envisions that the proposed organophosphate pesticide sensing system can be used by farmers to help reduce their pesticide usage by monitoring pesticide levels on crops in situ. The sensor will allow for wider screening and testing of fresh fruits and vegetables in the marketplace for pesticide residues, reducing lag time to market. The U.S. government should be interested in this product as it would facilitate testing of foods imported from countries that may not have effective regulatory mechanisms in place to assure that pesticide levels remain below EPA tolerance levels. Finally with the growing importance of organic food the sensor will allow these food products to be checked to insure that there was no fraud or mislabeling of such products. OBJECTIVES: The overarching goal of the proposed research is to determine the feasibility of using an LFE sensor with selective filtering in the sensing film to detect organophosphate pesticides. In order to realize this goal, the following objectives will be achieved. Technical Objective 1: Determine the feasibility of using LFE detectors to enhance selectivity for liquid-phase organophosphate pesticide detection The response of both coated and uncoated LFE detectors will be explored and compared to standard devices to determine if inclusion of such devices can enhance selectivity and sensitivity of the sensor. The LFE detectors will be examined with porous silica films, zeolyte films, and chemically selective polymer films. Technical Objective 1 is tentatively scheduled to be completed by 01 August 2008. Technical Objective 2: Determine the feasibility of detecting phosmet in blueberry juice using coated LFE sensors The response of coated LFE sensors will be measured when exposed to blueberry juices both with and without phosmet. Technical Objective 2 is tentatively scheduled to be completed by 05 December 2008. Technical Objective 3: Develop a sampling protocol for measuring the produce sample The sensor is a liquid-phase sensor. In order to deliver the produce sample to the sensor the produce must be rinsed and/or crushed so that the rinse water and/or juice can be measured by the proposed pesticide sensor. Technical Objective 3 is tentatively scheduled to be completed by 19 December 2008. The outputs of the proposed research include several activities. The first activities are the experiments being conducted to prove the feasibility of using the proposed sensor element for the detection of organophosphate pesticides. The experiments are described in more detail in the methods section below. The next activity is the survey of blueberry producers to develop the sampling protocol for introducing the sample to the sensor system. The survey will be developed in consultation with Dr. John Jemison, UMaine Cooperative Extension. The final activity will be the draft sampling protocol to be used in conjunction with the final prototype. The sampling protocol, by necessity, can not be finalized until the full sensor system prototype is developed. APPROACH: Task 1: Kick-off meeting The Mainely Sensors team will review the work plan and make modifications as necessary based on intervening knowledge gained, assign tasks, set deadlines for each task, and establish lines of communication. Task 2: Determine the feasibility of using lateral field excited (LFE) detectors to enhance selectivity for liquid-phase organophosphate pesticide detection Results will be obtained with bare LFE sensors and sensors coated with non-absorbing coatings, such as octadecyltrichlorosilane, to explore mechanical and electrical properties of aqueous solutions containing pesticides and interferents. Performance of these LFE sensors as probes of fluid viscosity and density will be compared to results obtained with the standard quartz crystal microbalances (QCMs) coated with inert films. Optimum coatings and coating methods using porous silica films, zeolyte films, and chemically selective polymer films will be deposited on LFE sensors. LFE sensors will be coated with both porous silica and zeolyte films and exposed to phosmet solutions and strobin solutions. The film that yields the best sensor selectivity and sensitivity will be chosen. LFE sensors will be coated with PECH and the film chosen in the prior experiments. The coated sensors will be exposed to varying concentrations of phosmet (< 25 ppm) in deionized water to determine the ability of the sensing films to detect phosmet. The same sensors will be exposed to strobin in deionized water to demonstrate selectivity in a simple medium. These experiments should show the advantages of the LFE devices compared to standard devices. Task 3: Test the LFE sensor with blueberries The LFE sensor with the optimized coatings will be exposed to blueberries treated with phosmet and organically grown blueberries, not treated with pesticides. The blueberries will be crushed and the juice will be delivered to both the QCM sensor and the LFE sensor and the results compared. The samples will be evaluated using liquid chromatography at the Dept of Food Science at UMaine. Task 4: Test the LFE sensor with blueberries with a single organic interferent The LFE sensor will be exposed to blueberries treated with phosmet and methanol. The juice used in Task 3 will have varying concentrations of methanol added to the sample in the delivery system. The juice will be delivered to both the QCM and LFE sensor and the results compared. The results will be compared to those obtained in Task 3. The samples will be evaluated using liquid chromatography at the Dept of Food Science at UMaine. Task 5: Develop a sampling protocol for blueberries Mainely Sensors will survey local blueberry producers to develop a sampling protocol for producing the liquid that is delivered to the sensor. A rough prototype of the package must also be developed, so that delivery of the sample to the sensor can be demonstrated. Task 6: Project Management Mr. French will be assisted by Mr. Joe Arsenault in administering the contract and satisfying all reporting requirements
