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A Lateral Field Excited Organophosphate Pesticide Sensor

Investigators
French, Lester
Institutions
Mainely Sensors, LLC
Start date
2008
End date
2009
Objective
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.

More information
NON-TECHNICAL SUMMARY: 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.

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.

PROGRESS: 2008/05 TO 2009/04
OUTPUTS: Outputs -- A list of 150 potential chemical interferents, both natural and man-made, found in blueberries was compiled. Sensors have been fabricated and are being prepared to detect the organophosphate pesticide phosmet in solution. Extensive research into chemiselective films for phosmet has been conducted. The polymer film, polyepichlorohydrin (PECH), is being used as the selective film on the lateral field excited (LFE) sensor platform. A procedure for depositing uniform PECH films with repeatable thicknesses has been developed. In order to develop a sampling protocol for the organophosphate sensor that allows for ease of use in the field, discussions and visits to blueberry growers and staff at the Wild Blueberry Extension at the University of Maine have been conducted. The blueberry growers contacted to date use organic farming methods. The growers were informally surveyed so as to determine a sampling method that will most seamlessly interface with their current processing operations. Dissemination -- As part of an existing National Science Foundation (NSF) Research Experience for Teachers (RET) grant at the University of Maine, Mr. Terence Tibbetts, a teacher at the William S. Cohen School, Bangor, ME worked with blueberry specialists and growers from June through August 2008. His dual purpose was to determine the best practices in the pest management of Maine wild blueberries and to use the gained knowledge to educate his students on sensor research.
PARTICIPANTS: Individuals PI, Lester French -- Mr. French has been in charge of coordinating all aspects of the project. He has worked with all collaborators in designing the experiments and has performed all of the research involved in identifying the appropriate films for enhancing the selectivity of the LFE organophosphate pesticide sensor. He has been responsible for purchasing the materials necessary for the project. Mr. French has visited with some blueberry growers and discussed sampling protocols for the sensor under development with them. Mitchell Wark -- Mr. Wark has been in charge of the testing protocols for the LFE organophosphate pesticide sensor. Mr. Wark is also responsible for preparing the sensors with the PECH films. Additionally, Mr. Wark has been instrumental in determining the applicability of an antibody selective to phosmet for the LFE sensor. Joe Arsenault -- Mr. Arsenault has been responsible for all aspects of administering the grant internally. Dr. John Vetelino -- Dr. Vetelino has been responsible for recommending modifications to the work plan and reviewing experimental and sampling methodology. Mike Fecteau -- Mr. Fecteau is responsible for the fabrication of the LFE sensor platforms for the project. Partner Organizations Laboratory for Surface Science and Technology (LASST) at University of Maine, Orono, ME -- LASST is where all of our sensors are fabricated. Additionally, Mainely Sensors has a facility use agreement with LASST so that all sensor testing occurs in LASST laboratories. Collaborators Dr. David Frankel, University of Maine -- Dr. Frankel is a consultant on the project. Dr. Frankel has assisted Mainely Sensors by reviewing our experimental methodology and making suggestions to improve our test setup. Dr. Carl Tripp, University of Maine -- Dr. Tripp has provided advice and support for the films required to enhance the chemical selectivity of the LFE organophosphate sensor. Dr. Brian Perkins, University of Maine -- Dr. Perkins assisted Mainely Sensors in obtaining the chemical composition of Maine wild blueberries. Additionally, Dr. Perkins has provided guidance in the use of antibodies to enhance the chemical selectivity of the LFE organophosphate sensor. Training or Professional Development Terence Tibbetts -- Mr. Tibbetts, a teacher at the William S. Cohen School, Bangor, ME worked on this project as part of an existing National Science Foundation (NSF) Research Experience for Teachers (RET) grant at the University of Maine, from June through August 2008. Mr. Tibbetts was responsible for contacting blueberry specialists and growers concerning their use of pesticides and their processing methods. The goal was to determine how best to integrate the LFE organophosphate pesticide sensor into existing processing facilities. Mr. Tibbetts obtained information regarding organic farming methods and was invited to tour some farms and processing facilities.
TARGET AUDIENCES: Target Audiences We are serving the wild blueberry growers of Maine by developing a sensor for the detection of organophosphate pesticides on Maine wild blueberries. We have been working to develop a sensor that will meet the needs of this audience by providing them with the information that will help them obtain data about their pesticide usage. Eventually we hope that this instrument will allow growers to adjust their application of pesticide to the crops so that a balance of pest management and public safety is reached. Organic farmers are interested in this sensor, because it will allow them to determine of there is pesticide drift from non-organic operations onto their crops. Efforts A broader success of this project has been the collaboration with Mr. Tibbetts, a participant of the NSF RET program at the University of Maine. Mr. Tibbetts feels that his research experience during this past summer will reinvigorate his teaching of science to his middle school students. He feels that he better understands the trials and tribulations that go into groundbreaking research. If this experience results in his students having a greater appreciation of science and how it can impact society, it will be well worth it.
PROJECT MODIFICATIONS: The major finding of the project has been that a film to enhance the selectivity of the PECH film for the detection of phosmet is not practical due to the large amounts of chemical interferents in blueberries themselves and from chemical surfactants, pesticides, and fertilizers. Thus tests will be performed with only PECH films on the sensor to determine if this film provides sufficient selectivity for the most common interferents, such as blueberry juice, and organic and chemical fertilizers.

IMPACT: 2008/05 TO 2009/04
The large number of chemical components that naturally occur in blueberries made the choice of a film to enhance selectivity very difficult. After many discussions between the project participants, it was decided that the use of a selective film to enhance the selectivity of PECH impractical. It was after discussions with organic blueberry growers that it was determined that exposure to any pesticide residue was detrimental to their operations. Thus, they were interested in a sensor that was sensitive to the entire class of organophosphate pesticides. Thus the sensor with PECH only is determined to be sufficient for this task, if it does not respond to the natural components of blueberries or the chemical composition of any fertilizers, both organic and chemical, used on the crops. Another outcome of the research for chemiselectve films was that organophosphate pesticides can also be detected using antibodies directed against the pesticide. There are test kits available that are used to detect some pesticides and custom antibodies can be developed at a cost in both money and time. With Mainely Sensors experience in attaching antibodies onto our sensor platforms, we feel that this approach may be worth investigating in Phase II. There is a great deal of interest from organic growers in the ability to measure organophosphate pesticides. The reason is that they are concerned that if a nearby blueberry farmer applies organophosphate pesticdes to their crop, then the pesticide could drift onto the organic farmers' blueberry crop. The organic farmers' would like the ability to measure the drift, if possible. Mr. Tibbetts found that his research experience during this past summer reinvigorated his teaching of science to his middle school students. He feels that he better understands the trials and tribulations that go into groundbreaking research. He stated that if this experience results in his students having a greater appreciation of science and how it can impact society, it will be well worth it.

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
View this project
Project number
MEK-2008-00217
Accession number
213735
Categories
Pesticide Residues
Chemical Contaminants
Education and Training
Commodities
Produce